Is converting your .250 Savage or .257 Roberts to the A.I. version worth the expense of having them reamed out? Is the difference that noticeable in the field?

Jim

Had a 257 AI at one time, an acquaintance decided it made the perfect coyote rifle at 350 - 400 yds and talked me out of it.

The biggest benefit is extended brass life if you neck size after fire-forming in the individual chamber.

Normally, you derive about 4% - 5% greater velocity with a corresponding 4% - 5% increase in propellent due to increased case capacity.

Some will tell you the 40 degree shoulder will provide more efficient powder burn than the standard case will. That's theory, not science to me.

I'm down to only one AI wildcat at this time - had as many as four in the past. I was experimenting for the ultimate for the particular cartridge. Now, I'm satisfied with the standard cases, but do have a few necked up or down from the original.

One thing about an AI - dies are more costly and the chambered rifle is harder to get shuck of, short of rebarreling/rechambering back to standard.

Jim here's a place you can rent the reamers if you want to open up those chambers. This can be done by hand, but really works best if the barrel is removed and set back a thread or two to clean up the chambers.

http://www.4-dproducts.com/display.php?group=Rifle+Calibers&PHPSESSID=45efb7f7d032e8883471737a383d1a8d

The brass is all custom fireformed, no SAAMI specs to go on, expensive or custom dies required, not possible to go back without a new barrel. I had heard the brass didn't last as long, but I don't own one and don't know that as fact.

Seems like a lot to go through for only 4% better velocity and more expensive to shoot...

actually velocity only increases at 1/4 the rate of case capacity. i'm an ackley fan but also a realist, that being said some cases respond better than others to improving. the more taper in the parent case the more there is to gain. brass life will certainly be better, my experience has been trim 'em after the fireforming to square the mouths and thats pretty much it for the life of the brass.
fred zeglin has a chart on the 4D page that lists the gains for the various parent cases. fred is also working on an article about the various cartridges, i believe he said it is for the '08 or '09 gun digest... not sure. anyhow, i like 'em but there is more to a cartridge than just it's muzzle velocity.

Well said big dan. I understand that somebody is going to make the 280 Rem AI a commercial case and it comes pretty close to the 7mm Rem mag velocities. If it wasn't for what this does to resale value I'd do it to my 280 Remington Mountain rifle. Of course I keep turning the idea of rechambering my 8mm Rem mag to an 8mm Ultra-mag and that's a silly idea also. I sure don't need any added recoil there.

I use just plain old Lee dies to reload my 30-06 AI and it seems to work just fine. Now, I just neck size the brass and use light loads to fire form, so I have no ned to get "special" dies for it.

On the other hand I am going to get my .243 improved and when the .223 in 788 finally just won't shoot any more I'll get it rebarreled to .223 AI. Why? Well, because I can, and I'm not all that concerned with resale value.

RJ

With three fired cases Lee will make up a deluxe die set with both a collet neck sizer and a full length sizer for 50 bucks. That's a real deal.

It depends alot on the particular cartridge being considered. Often much of the gain attributed to AI can be gained from simply reloading of the original cartridge. There was an article on which cartridges gained the most from AI'ing. IIRC the .250 Savage was one of the top ones, which I suppose isn't surprizing since the case capacity is rather small for .25 caliber so it would have a lot to gain from an increase in case capacity. The .257 Roberts AI appeared to have a reasonable gain, but that's compared to the standard velocities which were quite mild. If one compared the AI to the +P Roberts, then the gains were no where near as impressive. There are of course supposed to be other 'advantages' of AI'ing, such as have been mentioned (usually recoil, brass life etc. are mentioned). One thing I would like to learn more about is what the implications are of firing a 'standard' round in an AI rifle. Supposedly being able to fire the original cartridge is an advantage of AI'ing (over some other 'wildcat'), but I've not seen much about the implications of doing so as they relate to velocity and accuracy.

DakotaElkSlayer:

Wether it is worth it to convert a rifle depends on several things.

First; if it is a real tack driver, don't do it. Buy an action and put a barrel chambered for the cartridge of choice on that action.

Second; if the rifle is showing very poor accuracy it probably will not improve by rechambering. Rechambering may improve mediocre accuracy if the rechambering corrects some other problem.

If you want a little improvement, improved cartridges will give you this, if you want a lot of improvement go to a different cartridge or class of cartridge (ie; from standard to magnum). I like the improved cartridges, but I think some people expect much more than what they can get with an improved cartridge.

Anyway they are all fun to shoot.

Regards,
Gene

The question is asked if firing the original parent cartridge in an improved chamber has any adverse effects.

Answer - in my experience with the various improved chambers I've owned, the only adverse effect was a loss of velocity and POI. Otherwise, the firearm functioned normally and the grouping was acceptable - only not in the same area or the AI grouping. Normally lower, but centered.

not sure about velocity loss with fireform loads, but as i recall the point of impact diff in my 338/06AI was pretty much non existant. been so long since i formed brass for it that i can't say for sure... however since the only things that i seem to remember are things that don't matter i'm surprised that i can't tell you the difference even tho it's been ten years since i formed brass for it. load it sensible and the brass will last forever,it's been 10 years now and alls i've done is anneal the necks this past summer. dont know that i needed too, never lost a case to a neck split, just wanted to try my hand at annealing.

Big Dan has it. As I've said before, they ought to be called "Ackley Exaggerated" because there's so little real improvement, but so much exaggeration of the results.

The greatly increased velocities reported by some are the result of greatly increased pressures, plain and simple. There is no free lunch in ballistics, and adding a bit to case volume isn't magic. In fact, you have to add more powder just to get back to the ORIGINAL muzzle speed when you add case volume. By the time you do that, there's little or no extra room left to add still more powder.

The 1/4 rule mentioned is valid. Whatever you add to the case in percent of capacity, you'll get one fourth of that in percent of velocity. Example: you increase your 309 Hohum case by 12% capacity when you Ackley Exaggerate it. If you got 2800 fps before, you'll get 3% more - a whopping 2884 - for your trouble and expense.

I guess I'll have to chime in, owning both a .250 Savage and a .257 Roberts.... two of the greatest candidates for the AI conversion.

Nothing against those who do the conversion, but I can't think of one single reason to alter either of my guns. They're both working great, as is!

Were I to start with an entirely new project (plain receiver, barrel blank, and a chunk of wood), then sure, it' s just another chambering choice. Boils down to reamer / gage costs, and 'want.'

It's kinda fun reading about this and dreaming of all those different things you can do, but I'll go along with MikeG and gene, why not just get a cartridge that has more case capacity to begin with? Go to a 25-06 or a 257 Weatherby for that increased velocity. After all you can never own enough guns. I'm safe saying that cause my wife isn't watching.

I think I'll just leave my 280 chambered like it is. It sure smacks the deer, at least it did for my friend whom borrowed it last year. I've yet to get out to hunt with it other than smack a few coyotes.

I guess I've just never understood all the wildcatting going on, folks spend lots of bucks trying to make a cartridge do something that another factory cartridge already does.

I really shouldn't gripe, when I had my little gunsmith shop folks sure made me a bunch of money with their urge to be different. Go for it guys.

Because a sphere has the least surface area for a given volume, I suppose the spherical case would be most efficient. That is, it would provide the most pressure from the least powder for its volume. That's why squaring up a shoulder should help a little. Less surface are for the volume. But this is only a small improvement over the parent case in many of the AI versions. Most of the efficiency improvements that have been demonstrated to be significant seem to have happened in short fat cases, like the 6 mm BR. They come a lot closer to approximating a sphere than blowing out a .30-06 shoulder would do. I would guess, therefore, that opening the neck up to .308 and pushing the shoulder back on a .284 Winchester case would let you duplicate .308 ballistics with a little less powder and case volume and in a shorter action. That kind of thing.

The only way I could see the AI improving a normal shooter's performance would be if the steeper shoulder angle's effect on powder burn reduced velocity extreme spread for long range shooting. It might, a little. The added fluid constriction is a little like adding to your start pressure, thus making bullet pull variance a little less significant.

I've never owned an AI chambering. You guys who have had them, have you noticed any improved velocity consistency over what the parent cartridges gave you with the same powders?

The question, whether it is “worth-it� to “Improve� a cartridge, or “not worth it,� is certainly an interesting way to start a long discussion.
There is a great deal of miss-information floating around about P. O. Ackley, Improved cartridges and the degree of Improvement a cartridge is given by the simple means of changing the shape of the chamber and the cartridge case – I am not an “expert� on the subject.
If your only point of study is P. O. Ackley’s book: Handbook for Shooters and Reloader’s� you are viewing a very large area of discussion through a soda straw. P. O. Ackley’s most interesting writing and comments on rifles, cartridges and reloading are scattered through many years of magazine articles and small contributions to a few books. A good place to begin your studies is Charles S. Landis book: “Woodchucks and Woodchuck Rifles.�
The more you read the writings of P. O. Ackley the more clear it becomes there were a great many more reasons to improve a cartridge than to achieve higher velocity. Reading articles written by P. O. Ackley and Robert Hutton in Guns & Ammo Magazine from the 1950’s and ‘60’s will begin to give you a better perspective as to why so many cartridges were “Improved� in the first place. Robert Hutton was searching for the “Ideal� long range target cartridge and he left no stone unturned in quest for high velocity and long range accuracy. Many of us do not realize it but the .30-30 Ackley Improved started life as one of Robert Hutton’s experiments in search for the ideal long range target cartridge. The first rifle built for the .30-30 Ackley Improved cartridge was built on an FN Mauser action with the goal of driving a 180-grain bullet to a velocity of 3,000 fps. Almost as an afterthought two Model 94 Winchesters were improved and very little detail information was revealed on these rifles. The reason for this lack of enthusiasm or detailed information was simple; the testers knew the 20� .30-30 AI provided very little improvement over the standard .30-30 with a 26� barrel. Robert Hutton felt there was no significant improvement to be gained by improving the Model 94 Winchester.
Pre WWII and in the immediate post WW II years there was not a great deal of variety in canister powders available to the home hobbyist and there were fewer rifles, or component bullets, available that would meet today’s accuracy expectations. There were not many factory cartridges available to enthusiastic rifleman or varmint hunter. The only real option was a wildcat cartridge, built on a custom rifle, using home made bullets hand swaged from custom dies.
In my experience the .22 Hornet Improved provides considerably more “improvement� than simply increased velocity.
The .25-35 Ackley Improved is a cartridge which exploits the two most important aspects of the Improved case shape: reduced breech thrust and increased velocity. Anyone who has worked with a Thompson Contender chambered for the standard .25-35 WCF cartridge will attest to the very real improvement provided by the simple act of simply straightening the case walls and altering the shoulder angle. If you are willing to accept loading the .25-35AI cartridge to higher pressure levels the increase in velocity is surprising. Either way the improvement in the usefulness of the .25-35 WCF cartridge is real and may be duplicated by any skilled handloader.
It is well known on this forum I am a big fan of the .307 Winchester. I have followed this cartridge from its wildcat beginnings in the 1960’s and bought one the first one I was able to find. I reamed my first .30-30AI chamber because I was reading a great deal of internet nonsense about the .30-30AI cartridge and I was seeing quite a bit of load data posted that I believed was unsafe for use in lever action rifles. A quick check on some of this load data using the Powley Computer for Handloaders made it clear these claims were not realistic. Actual use of the .30-30AI has revealed this is indeed quite an interesting cartridge. The 20� barreled .30-30AI cannot safely equal the performance of the 20� .307 Winchester but it does deliver a significant performance boost for the Winchester Model 94AE or Marlin 336. This increase in performance does indeed come at the expense of higher operating pressure and requirement for increased care in handloading the ammunition.

I have posted this quote before and I hope I will be forgiven for posting it again of this forum. In the December 1953 issue of the American Rifleman William F. Wieman from the H. P. White Laboratory wrote an article entitled: “How Improved is it.� In this article a .30-06 rifle was reamed for the .30-06 Improved cartridge and then loaded to standard .30-06 pressure with the astonishing result of little to no improvement.

In the October 1954 issue of the American Rifleman P. O. Ackley answered his critics with a point paper entitled: “Improved' Cartridges.�
Both of these articles are interesting reading and reveal two different philosophies with regard to handloading ammunition by the home hobbyist. Ackley’s article contains my all time favorite gun writer quote:

“At the beginning of these comments certain things were pointed out as possible improvements, but nothing was said concerning pressure. Whether the handloader or wildcat enthusiast is right or wrong, he is interested in several things, most important of which are increased velocity and whether the bolt stays in the gun. If he can achieve these two results without serious complications, he is not overly concerned with the actual pressure readings in pounds per square inch.
From the handloadcr's point of view, the amount of bolt thrust is of great importance. The pressure transmitted to the walls of the chamber can be safely-contained by the use of high tensile strength steel in the barrel.�

The question of whether or not Improving a cartridge is worth depends a great deal on WHY you are Improving said cartridge.

My 257 Roberts didn't gain much in speed when converted to A.I., but it definitely lost its powder sensitivity. For me that was the biggest advantage! My 280 A.I. is faster than The 7mm Reminton Mag. with a whole lot less powder, and its definitely worth it in every way that I can think of!

For me, it boils down to something you wrote, William:

"If you are willing to accept loading the … cartridge to higher pressure levels the increase in velocity is surprising."

That's the key to almost all the so-called "improvement" people report with AI cartridges - they're just running them at much higher pressures. They could likely get the same results if they just kept pouring powder into the un-improved cartridge until they achieved the same excessive pressure levels.

The world is full of shooters who think they know more than the professional ballisticians and professional metallurgists. Those are Ackley fans.

http://beartoothbullets.com/tech_notes/archive_tech_notes.htm/43

I am an ackley fan, and it is not because I think I know more than "professional ballisticians and professional metallurgists". A few minutes perusing Marshal's article sums it up better than I can. The bottom line is, that for a minor investment in money (much less than even a Stevens bolt action), and a very enjoyable investment in time(a couple of days shade tree gunsmithing with my father), I have two model 94's which are capable of still accurately shooting factory ammunition from walmart, with about a 75 fps velocity loss with 150 grainers, and have exhibited a 10% improvement with my preferred 110 grain bullet.

In closing, I would say that it is a personal choice, and I certainly won't belittle anyone for not "ackley improving" ol' Betsy. It was and is the right choice for me, and judging by the replies, for a few of us.

Gordon Taylor

No question that there are some sane Ackley fans. Sincere congratulations to all who are. But there are also far too many who think a few twists of a reamer can give Ol'Betsy another 300 fps with no consequences.

Unless you exceed maximum standard pressures for a given cartridge, it's not usually possible to get more than about 3% added velocity, even with the most radical case reforming. If that tiny addition is worth it to you, have at it.

Well, a very interesting read indeed.
I recently had my old beat-up Rem 700 BDL restocked and converted to an AI. This old rifle never really impressed me in the accuracy dept. I tried dozens of bullet and powder combos over the years and it was always just so-so. So, converting it was no great expense or loss if things didn't work out.
As it turned out I really like this new toy. It shoots very well, the brass seems to last forever and it just plain fun to work up loads for this semi-wildcat.
In the original 30-06 chamber max velocity with 180gr Partition was just under 2800fps before pressure signs showed up. In the AI chamber max velocity is just over 2900fps before pressure sign rear their ugly head. So, at Max pressure in my rifle the AI will produce just over 100fps more. Is that worth the expense etc., I duno, but it sure is fun to shoot and the brass looks cool.
I am seriously thinking about converting my CZ 6.5x55 to an AI next.

Steve, if you do some math, your new velocity is just about (drum roll, please) 3.5% more than before. So, unless you start trying for an even 3000 in that rig, you are among that enviable class of sane Ackley fans. Let us know how that 6.5x55 turns out, willya?

It's the guys who claim they're getting 22-250 speed from their 223AI that make my skin crawl.

Rocky, while many who load for Improved cartridges concentrate solely on high velocity it should not be our primary reason for selecting an improved cartridge. P. O. Ackley wrote on this subject several times and it is unfortunate he did not leave us some interesting, quotable paragraphs.
To be fair to many handloaders we must remember the manufacturers will not or cannot fulfill everyone’s needs or desires. We cannot dub them all Ackley fans. After all this would slight the accomplishments of Killbourn, Mashburn, Donaldson etc.
I do not consider the use of improved cartridges to be “real” wildcatting, just a variation. It is to the true wildcatters who have developed cartridges for special needs that we owe the tip of the hat. Even the wildcat cartridges which do not fill a “real need” are necessary simply because they answer the question: “What about…”
Here, I am thinking of the half dozen or so wildcatters who dreamed up the .307 and .356 Winchester cartridges for instance. Or a “gun crank” such as Ken Waters who dreamed up wildcats to save classic rifles with pitted bores: .350 Maine Guide and the .375 Express come to mind.
Wildcatters working with the .458 X 2” paved the way for the .450 Marlin – a cartridge whose performance capability was demanded by the consumer – but could not be safely met by manufactures using the .45-70 cartridge.
We the consumers have a great deal to thank wildcatters for, even if they are often painted with the broad brush of having “reckless disregard for the established safety procedures.”
It is off topic here but there are over 100 canister powders potentially available to the home hobbyist and very little useful data available for the older or less popular cartridges. There should be more classes given by men such as Fred Zeglin on common handloading tasks and in the fine art of working “outside the margins.”

Slim,

Thanks for pointing out the benefits of doing the AI in Contenders. Not having owned one, it never occurred to me .....

Some cartridges are pretty difficult to deal with in the Contender. The tapered cartridges like the .25-35 will sometimes give sticky extraction with published load data. Improvement of the case helps a GREAT DEAL.
<O:p</O:p
You have probably seen it but for those who haven’t David White’s comments in this thread are interesting.
<O:p></O:p>
http://shootersforum.com/showthread.htm?t=5813&highlight=ackley

Slim,

Thanks for the historical background, earlier. The only time I ever looked at going to an AI was when a friend and I were considering trying out the front ignition concept. Too many other things got in the way and stole our time, so we never did more than talk about it.

I did a quick lookup of case capacities in QuickLOAD. In its database, the .30-06 AI only has about 2.5% more capacity than its parent cartridge. The .257 Roberts AI, at the other extreme, has 12.5% more capacity. The .30-30 AI has 10.5% more capacity. If ballistic efficiency remained constant (and it won't, but for back-of-napkin guestimation, I am pretending it does) the velocity gain would equal the square root of the difference in powder quantity for a given powder in a full case. That is, stored chemical energy in the powder is proportional to the square of velocity when converted to kinetic energy by the gun (E=½mV²). The square root of 1.025 is 1.012, so the .30-06, with same ballistic efficiency would gain only 1.2% velocity, or about 32 fps out of 2600 for 180 grain bullets. Within the normal extreme spread of many load combinations. The .257 AI, on the other hand, would gain 6.1% (square root of 1.125 is 1.061). That's around 200 fps of gain in the range of .257 loads. So, I can see why, among those whose only interest is in gaining exterior ballistic performance, they could discount the .30-06 AI as a waste of time, while those with the .30-30 AI and the .257 AI would be singing their praises.

Steve4102's information reminded me of all the rifles out there that fail, somehow, to respond to conventional accuracy work. The AI conversion is certainly less expense than a new barrel, and makes a logical next thing to try. This, of course, is going beyond concern with external ballistics alone. I am still curious to learn whether the change in case shape makes for lower MV ES, typically, in the AI cartridges? That would be of value for long range shooters, quite regardless of the absolute value of MV achieved.

Unclenick, funny you should mention having a quote from PO Ackley himself. I happen to have a copy of the January 1964 issue of Guns and Ammo in which Parker Otto himself addresses a question about “overbore” cartridges, which we might extend to include the more radical “Improved” rounds as well.
Excerpts from Ackley’s long reply: “Overbore capacity is a term we use to describe a cartridge which holds more powder than the bore can handle. I suppose this is as good a definition as any, but we have found by experience that a certain bore size will handle only up to a certain amount of powder efficiently and from that point on very little increase in velocity is possible. (Example deleted- RR) As far as I know, no gains are realized by the use of overbore capacity cases. The only advantage that I know of concerning overbore capacity cases is the advertising angle. Great and glowing claims are made for them and seldom are these claims lived up to by the cartridge in question. At least there are many more things on the red side of the ledger than the black.”
Now, granted he was not speaking directly about his own style of cartridge “Improvement” in this question, but it does indicate that even Ackley himself knew that more isn’t always better. It is also true that other benefits have been claimed for AI cases besides case/powder volume – and some may be true. But I think that on the issue of volume and velocity, Ackley and I agree.
Interesting, no?

Here's a site about internal ballistics. Check out "Velocity vs Case Capacity and Barsness' rule of thumb".

http://www.fabriquescientific.com/

Bye
Jack

i like my ackleys, there is no doubt about that. but that being said, you have to use your head, remember, back in the heyday of wildcatting the technology wasn't there to verify pressure and i have to seriously questions the chronographs of the era. i like to tinker around and i prefer to have something a bit different than everyone else, mabey thats why i got into ackleys, dunno.... actually i do know, Mark Hinrichs was working at brownells at the time(he's the guy who build the first 338 & 375 Scovills for Dave Scovill) and i had stopped by there one day when i was up visiting my dad,( i grew up about 20 minutes north of Monte) anyhow back to my story, i had taken along an unfired higgins 270 that i bought out of an estate, it had an odd screw spacing on the rear bridge for the scope base so i wanted them to look at it. anyhow, i was long since sold on the 338/06 and that was the reason that i had purchased that rifle ( that and who could pass up a virgin FN action?!?!?)
anyhow we got to visiting and hit it off rather well as i have a tool & die background and was working as a journeyman machinist for BN at the time, we had a lot of good stuff to chew over. he felt that the 338/06 was great but to make it better he said go AI... we visited about it for a bit, he told me that he bought 338/06AI dies from redding by the 5 pack. that was about 10 years ago and i have appreciated every bit of his advice!
not every cartridge is a good candidate to be improved, which is something he told me, he also impressed upon me that velocity is only one of a few reasons to improve a cartridge. now all that being said, i had Fred Zeglin do some sight work on my 1895 405 win, we were chewing the fat and got to talking about improved stuff, which he and i are both fond of. his advice was to take 5 pieces of unfired brass once you have your load that you want to use, load those 5 pieces and fire them 6 times, if the primer pockets stay tight you are safe, if not, you're flirting with disaster. sounds pretty smart to me weather you're shooting an improved cartridge or not considering the price of components these days.
we all wanna go fast, we just gotta use our head.

by the way with my 6.5X55AI i have safely gotten 2950 fps with 130gr barnes tsx's using ramshot magnum... 5 shots will tear one ragged hole and brass life is great!

My PACT says that my .308 Improved 40 (yeah, i know, P.O actually never did this one) will do 2965 fps with a 150 gr Silvertip with just over 44 grains of 3031. It will put three shots touching just about anytime i want at 100 yds, and this is on a Sako AII. I can attest that the 26 deer it has taken didn't complain about being shot with anything resembling an Improved Cartridge. And, i have no pressure signs, so i would think i could tip the can just a bit more, but i don't want to.

Its fun, there's just a tad of snob appeal, and i like having something the average person doesn't; and i recently had a Ruger 77 reamed to .257 AI. Even the published figures are less than a .25-06, but its what i want, just because its different. Some people drive Chevies, some drive Fords. If i was really a velocity freak, i'd probably shoot Weatherbys.

But, its a fun hobby, right??

Yup - it is a fun hobby. My thinking parallels yours. Sometimes it's just fun to have something different to play with and call it your personal own. None of the ones I've had or have will do much that some other commercial chambering won't do, but it fits a particular niche in my supposed needs, so they suit me.

I well know I'll never get the costs back it took to make them, however, I'll train my grandson on how to load and fireform for them and maybe they will live on for a few more generations.

I think having case trimming cut to almost zero is the prime benefit of the AI cartridges, and I have a slew of them. The Barsness rule is dead on and has been for all of my AI's, from 22-250 to .375 H&H. As aforementioned, the heavily tapered cases show the most increase. I'm with K-dub and the earlier posters who like the "cool" factor and not having a rifle that every Tom, Dick And Harry have. For me, they scratch this itch very well.

Well, I can see and appreciate the pro and con responses....
To be upfront: I never had an AI firearm!!:cool:
I have a .375X284 and I think it could be helped by going AI. BUT for my next project (there are always next projects for us junkies...LOL), since I'm a .375 fan, I'm planning a .375X348AI on a .303 Martini Enfield action! While using a straight barrel, I will have the option of rebarreling to another action, if the Martini has some problems with pressure/cartridge..etc. (I still have some Czech and Arisaka 38 milsurp Actions! If the Martini has a problem, I don't think I would try a Lee Enfield Mk1, 3 or 4! Maybe a P14.
So, in this case, the .375X348AI wouldn't be any guess, you are at the perceived or real optimum!

@Steve4102
I am seriously thinking about converting my CZ 6.5x55 to an AI next.I think you would be better off with a 6.5X284! You just need the reamer and whether you use the regular, Norma or an AI style reamer, THIS would be a REAL improvement!
just my 0.02 cents Canadian (IT'S PARR NOW!!:D)
Merry Xmas folks

I don't know why people expect us to question everything else in life except reloading data. I like reloading manuals, use them all the the time, but I get my gospel from the bible. The same people who bring us cross-bolt safeties on leverguns and 14 lb trigger pulls edit loading manuals. I exceed loading manual loads all the time and haven't blown up any thing in the 35 years I've been loading ammo. Ackley hinself would be the first to tell you that if you won't exceed factory loads then theres no reason to improve a catridge. Wildcatting is for people who have an inquisitive nature and like to push the envelope a little just to see what happens. I recently started loading for the 350 Rem Mag. I like 250 gr bullets. The book tells me that 54 gr of H4895 produces 2497 fps at 53,200 PSI. I work up to this load and chrono it, about 2450 fps in my gun. This is disappointing to me because the firearm used to work up the load used an 18 1/2" barrel and my rifle has a 22" barrel. I'm about 100 fps slower than I expected. I start looking for areas that can be improved. First thing I notice is that there is alot of space between the bullet and the front of the magazine in my rifle. The book lists 2.800 as max oal, but I find I can use 2.880 in my rifle with no problems. THis gives me alittle more space for powder. I also check pressures in the book and see that no loads exceed 54,000 psi. This seems alittle low for a belted magnum casing. I look up the 6.5 Rem mag, sister cartridge to the 350, and see that it is regularly loaded to 62,000 psi, same casing, same rifle. Maybe the powder is the limiting factor, no, H4895 is loaded in several belted magnum cartridges to pressures in excess of 63,000 psi. I decide to experiment and increase my oal to 2.880 and powder one grain at a time . I check for flat primers, excessive case stretching, incipient head separations, hard extraction etc. I reach a load that gives 2730 fps with the 250 gr bullet that gives no pressure signs in my gun. I am willing to accept the increased muzzle blast and recoil in exchange for the better balistics. I have reloaded casings 3-4 times without problems. This is an acceptable load to me, even though it exceeds book numbers. I shot two deer with it this year with perfect satisfaction. Cartridge designs like the 30-30, 30-40, 250, and 257 are limited by poor cartridge design. Excessive bolt thrust and poor case life at reasonable pressures attest to this. A simple rechamber job doesn't seem out of line with the benefits. If you don't think a gain of 200 fps is worth the effort than theres no need for a 300 win mag ,as thats all the gain you'll get over a 30-06 with a 180 gr bullet. My feeling is that there hasn't been any significant improvement in cartridge design since 1930. There won't be until something better than nitrocelllulose propellants are invented. Hope I haven't been to lengthy. Standing by with fire extinguisher handy.

You go right ahead and pour in all the extra powder you want, if you think it makes you look or feel better. But how you'll look and feel with a bolt sticking out of your eye socket is another matter.

You cannot repeal the laws of physics because it sounds like fun. All the Ackley fans who have stopped praising their toys stopped because they're dead or maimed. You can be next!

I'm sorry if that sounds rude, blunt or crude. But I'll not change my stance simply because somebody is offended.

All the Ackley fans who have stopped praising their toys stopped because they're dead or maimed. You can be next!

Rocky, I think everybody gets it, you don't think much of the A.I. cartridges. The statement of yours I quoted above is asinine and you know it.

Well, Ken, perhaps. But if those who USED to praise AIs but have STOPPED praising AIs - there must be some good reason. And that good reason speaks more eloquently against AI than any argument I might make.

But I take your point and won't post on the topic again.

I'll stand clear of the Ackley cartridge argument, since I've never worked with those, but will remind everyone to be civil. Looks like you sorted that out before it went too far, so I won't lock the thread, as board rules require me to do when the flames get too hot.

I will, however, repeat a safety comment for Tanker that I put up yesterday in another thread. I'm not sure why, but psychologically, people are inclined to believe numbers on digital displays blindly. None of the chronometers we buy come with certificates of calibration, that I've found. Even if they did, unless you can duplicate their calibration lighting conditions, a guarantee of precision wouldn't be worth much. Still, we tend to believe their digital number displays with no independent coroboration. I had the experience of shooting the same loads in the same .308 rifle over a Chrony and an Oehler 35, set up on adjacent firing points on the same day. The Chrony averaged 2700 fps for the load, and the Oehler and its check screen averaged 2500 fps. So 200 fps error is not at all out of the question for these gadgets.

Chronographs are wonderful tools for measuring relative variation. ES and SD are accurate on them as a percent of the mean they measure, but most of us have no way to validate the accuracy of that mean. This is why the manufacturers recommend you do not use velocity measurements to determine loads.

As to pressure signs, you can add the chronometer to your list. When you increase a powder charge without getting the expected increase in velocity, that means something is making more room for the powder to burn in, and that something is usually the chamber. However, I am unaware of any pressure sign that has not failed to work under some circumstance. Using them collectively, as you are, is a good move, but add the chronometer in to get yet another, and still, don't put too much faith in them.

I put a version of the load from the manual you described into QuickLOAD. I don't know your bullet length or the fired capacity of your cases? Both affect pressure significantly for a given charge and COL. The default case capacity in QuickLOAD is 72 grains. Barely over that of a 35 Whelen, so the test cases were probably bigger inside. In particular, Winchester tends to semi-balloon head their cases, now which adds several grains of room. In any event, the default case capacity, loaded with a 250 grain Hornady spire point over 54 grains of H4895, predicted 66,000 PSI. This is by the CIP method, whose maximum pressure for this cartridge is listed as 62,366 PSI (4300 bar). That pressure difference from the manual is partly the low computer model default case capacity, but it is likely also to be partly my bullet choice. The database has that Hornady bullet length as 1.32". If I change to the Speer Grand Slam, which is 1.225" long, the pressure prediction drops to a much more reasonable 58,685 PSI.

I hope, by the way, that disabuses you of any notion that bullet weight alone determines what load is safe? Pressure can change quite a bit between two same-weight bullets. It just depends on how far their bases are seated into the cases?

To better model your loads, I next increased the default case capacity until a 2.800" COL load gave a 53,200 PSI prediction with the Grand Slam bullet. That matched the pressure to the manual pressure (though I don't know what bullet or case they used). The case capacity was then 74.74 grains (exact predicted pressure was 53,213 PSI). From an 18.5" barrel, the predicted velocity is 2,359 fps. Far below the manual's claim. From a 22" barrel the prediction is 2,446 fps. Within 4 fps of the 2,450 fps measurement you reported. So, it may be your chronometer is doing pretty well, despite my warning. At least, whatever error it has comes close to the QuickLOAD predicitions for this load at the manual's peak pressure value.

Now I can take a stab at calculating the pressure you're getting from your final load, and be pretty confident that the computer model isn't too far off. QuickLOAD has no way to know your rifle's structural details, so it will not allow for chamber stretching. Thus, your actual charge may be higher than predicted. If it is, that is another pressure sign because it means things are starting to stretch, even if not enough to be obvious on a fired case. Again, all the common pressure signs can fail to appear until was too late.

(WARNING TO READERS: the load discussed below is not to be considered safe. It is described for informational purposes only.)

So, again, I use the Grand Slam and the 74.74 grain case water capacity figure. If I seat the bullet out to 2.880" and start adding powder, it takes about 62.1 grains to get to the 2730 fps number you measured. The predicted pressure, at that point, is 77,807 PSI. Basically, it is a proof load. It's regular use should cause rapid increase in throat erosion and extra fatigue of the bolt lugs and receiver. That it produces no conventional pressure signs is perfectly possible. Many guns do not show any until they are more than 10,000 PSI above published maximums, but wear and tear on the gun is for real, and it should be weakened by a steady diet of this load. There are no guarantees one way or the other, due to design and mettallurgical differences between different guns, but I would be wary.

If you are using more powder than 62.1 grains, you are likely starting to get stretching and should back down despite the lack of pressure signs. If you are using less, then I probably still haven't got the computer model quite close enough, and would need your actual bullet length, fired case water capacity, and, if possible, bore dimensions to do any better.

Great info, Nick - I hope everyone takes the time to read and understand what's being said.

I have several AI's in the vaults, simply because I wanted something a little different from the run-of-the-mill factory offerings. Lots of fun in fireforming and tweaking loads to the individual sweet spot. The maximum loads listed for the standard cartridges have been ventured over - that's the goal of the AI treatment. However, nothing radical and pressure signs/chronograph readings have been closely examined. I'm not a velocity freak, just wanting the best accuracy and case life.

One thing UncleNick's info doesn't address is the difference in chambers. Some are at SAAMI minimum and some are at the maximum. This will have a bearing on chamber pressures as well as other items mentioned. One of the best ways to have dramatic pressure increases is to poke the bullet ogive into the bore lands. Seating depth is critical in this regard.

Tanker - the main reason we try to adhere to the reloading manuals recommendations is in recognition that every firearm is unique unto itself and what may be perfectly safe in your particular gun will wreak havoc with someone else's. There's a lot of marginal firearms out there with the same chamberings done by backyard gunsmiths which don't need excessive pressure ammo fired through them.

Well, Ken, perhaps. But if those who USED to praise AIs but have STOPPED praising AIs - there must be some good reason. And that good reason speaks more eloquently against AI than any argument I might make.

But I take your point and won't post on the topic again.

@Rocky,
Did you read this??
http://shootersforum.com/showthread.htm?t=5813&page=2
Article #26 from David White.
I think it would lessen your assumptions a bit!
Regards

Wolf

Actually the load I use is several grains less than Unclenick figured. I thought the final pressures would be between 60-65,000 psi. I don't feel this is excessive for a belted magnum. This rifle is my big game rifle and once a load is worked up I probably won't shoot more than 100 rds a year, it is simply not pleasant to shoot. If I want lighter loads I'll pick a smaller caliber. The rifle is short, light, and very accurate which makes it a pleasure to hunt with. It gives comlete penetration without excessive meat destruction and leaves an easily followed blood trail. I am much more carefull about loads when I have multiple rifles in the same caliber.I once had two 45-70s and keeping the loads separated (one was a trapdoor replica) caused me alot of worry. I finally sold the trapdoor, it just worried me too much. All of your comments on the variables just prove my point. Aloading manual is a great starting point but you still have to think about what your doing. I recently bought a beautifull krag sporter in 30-40 and worked loads up for it. I keep it under book because it is too fine to chance ruining it, plus it is over a hundred years old. I sure wish I knew the history on that one. This is a great site. The level of Expertise is really amazing. I appreciate the amount work you did on your response and especially your gentlemanly attitude. By the way, this is actually the third 350 Mag I've worked loads up for over the years. I figured I fired a little over 1,100 rds using Three different bullets and two powders before I decided on this one. The process I used was alittle more involed than explained above for the sake of brevity.

One thing that hasn't been mentioned much is the fact that SAAMI pressures and the loads in the manuals usually are meant to be safe in obsolete fire arms. Some manuals actually do make distinctions between the old lever action Savage 99 and the modern Ruger 77 or the Rem. 700 chambered for the 250-3000 Savage. Same goes for the 45 Colt loaded in the Ruger Blackhawk vs. the old Colt Single Action Army.

The SAMMI pressures and the loading manuals cannot be correct for each and every fire arm can they? They rarely even agree among themselves due to different testing perameters. As limited as we may be with what most handloaders use for high pressure signs, I for one think they are pretty reliable. I don't usually exceed maximum published loads. Often times I stop well short of those max loads if my fire arm or my fired cases tell me to.

Seems to me that common sense and careful attention to detail are what is called for in safe reloading practice rather than blind faith in what a certain reloading manual might list. I always look at a half dozen different manuals anyway when working up a safe load to find a reasonable starting point. I then work up the load until I do see high pressure signs or a full case or good accuracy and trajectory. That's where I stop. If I see high pressure signs, I then back off a small amout until there are none. It is possible that my best load might exceed a published maximum in some manual but not in another manual. My feeling is that the individual hand loader must take responsibility in determining his own "safe maximum".

Rev

With the new fast powders available today, I think most Ackley improved rounds are a matter of personal interest more than a read gain in performance.

To clarify, you want a speed increase in the bullet, but not in powder burn rate; that would just raise pressures. In general, a slower powder in larger quantity is what increases velocity without raising peak pressure, because it sustains pressures in the barrel longer to further accelerate the bullet. If the case has run out of room, you still want a slower powder, but one with higher energy density so it fits in the case. The Vihtavuori N500 series is an example of high energy powders. Their manufacturer has gone from their normal single-base formulations to double-base formulations to increase the potential energy stored in each grain of powder weight as well as in each cubic centimeter of volume.

Keep in mind that conversion of chemically stored potential energy to ft-lbs of kinetic energy in the bullet is what a gun does. Ballistic efficiency is the percentage of that conversion that occurs, after loses due to putting kinetic energy into recoil and into expelled hot gases and unburned powder are taken into consideration. For a high power rifle, 30% is a pretty good number, while 45% would be rather high and 15% is pretty low. A lot of loads in the mid twenties exist.

I'm not a huge Ackley fan myself...at one time before there were the choices we have in rifles and cartridges today, it may have some merit with some cartridges...but those days are gone with the choices not only in cartridges we have today, but powder and bullet choices. Why AI a 280 Rem when you can just get a 7mm RM? Or an '06 when you can get any number of 300 mags? Etc., etc....Charshooter said it best with it's more personal interest.

Nick
30% is the efficiency rating I am looking for on my top end loads. 60 fps per grain of powder is another old measure of efficiency and the two estimates correspond to each other very well.
As you point out there are many very good load combinations in the mid 20% range that are very effective and accurate.
I believe we have lost our historical perspective on why Improved cartridges came about in the 1930’s. I have and load for several Improved cartridges. Some such as the 6.5 X 55AI are not really worth the effort. The .30-30AI is a surprisingly efficient cartridge but is seriously overloaded by some experimenters. The .25-35AI takes a cartridge which is a failure in the Thompson Center Contender handgun and rifle barrels and transforms it into a complete success – a surprising and efficient cartridge – if you are willing to load the cartridge to higher pressure.

Nick
30% is the efficiency rating I am looking for on my top end loads. 60 fps per grain of powder is another old measure of efficiency and the two estimates correspond to each other very well.
As you point out there are many very good load combinations in the mid 20% range that are very effective and accurate.
I believe we have lost our historical perspective on why Improved cartridges came about in the 1930’s. I have and load for several Improved cartridges. Some such as the 6.5 X 55AI are not really worth the effort. The .30-30AI is a surprisingly efficient cartridge but is seriously overloaded by some experimenters. The .25-35AI takes a cartridge which is a failure in the Thompson Center Contender handgun and rifle barrels and transforms it into a complete success – a surprising and efficient cartridge – if you are willing to load the cartridge to higher pressure.

William, are you saying 60 f/s per EXTRA grain of powder in an AI case. If that is, indeed, what the rule is, then my experience matches almost perfectly. With 95-100 gr. bullets in my old 6mm Rem. bbl. (when new), I got 3000f/s with 43.0 grs. of IMR 4350. In my 6mm. AI in a new match bbl. I get 3150 or slightly more with a 95 gr. bullet and 45.5 grs. of IMR 4350. Those are not the same bbl. or even exactly the same length. Both were what I consider max safe loads. It's pretty close to your 60 f/s rule, if I'm reading it correctly.

Rev

If you really want a hot 25 go to 257 stw over 4000 fps with 100 gr bullet 0r 25-300 win mag 0ver 3800 with same bullet

You're talking apples and oranges here, pphreed.

Guys are discussing tweaking the "older" cartridges before the advent of the modern WSMs, WSSMs, RUMs, etc, etc. The simple act of reaming the existing chamber to the AI configuration and then achieving better results over the parent case.

No doubt, the newer cartridges in combination with the newer propellents and bullets will exceed the AI'ing of the older cases, but it's fun, anyway. Plus, the cost involved doesn't match near what that new loudenboomerwhizbang is gonna cost. :D

While I agree with your point, kdub, couldn't a 257 STW (just an example, maybe not a good one) be made equally easily as a 257 Roberts AI, and thus the comparison is indeed valid?

Well, you got me. Can't find any info on a 257 STW in any of my books, so I'm at a loss to answer you on that one.

If it follows the trend of all the other STW's, then the case would be quite lengthy as compared to the 257 Robt's and then you're talking about a different length action/magazine which takes away from the simple chamber reaming of an existing rifle.

Always after something a bit different (I've said many times it's fun to have an AI chambering to have something different to lay on the shooting bench!), I've had about a half dozen rifles AI'd from .257 Robt's to 30-06. Some worked better than others. The oddball rifles in the vaults now are a 6mm/284, 6.5x257 Robt's AI, 6.5-06 and a 7mm Dakota. Lots of fun tweaking these cartridgesfor optimum accuracy/velocity. Most are not loaded to max for best performance. Still and all, they get the job done more efficiently than the standard case when considering the AI's and the other three non-standard cartridges (although, Dakota Arms sells factory ammo for the 7m Dakota) are just darn'd accurate chamberings in their own right.

Yeah, I don't know about the STW either. I know I've considered renting a chamber reamer and making my Marlin a .30-30 AI just for the hope of better case life and possibly a better ability to neck size only. But I doubt I'll do it. I must not care too much about performance of my .30-30 or else I wouldn't load plinkers with Unique most of the time! :)

Nothing wrong with plinkers, but Kdub is right. The .257 Roberts case is only 2.233 inches long maximum, while the STW is 2.850 inches long maximum, so there is no way for the .257 Roberts to be the parent of the STW, as it is for the .257 Roberts AI.

Nothing wrong with plinkers, but Kdub is right. The .257 Roberts case is only 2.233 inches long maximum, while the STW is 2.850 inches long maximum, so there is no way for the .257 Roberts to be the parent of the STW, as it is for the .257 Roberts AI.

At least some modern .257 Rbts. came in a long actions (same length as the .30-06, etc.). I know the Ruger 77 came like that at one time, because my best friend and hunting buddy bought that Ruger 77 (long ago - maybe 1977?) just for that reason. I think the Rem. 700 classics came with a short action and I really don't know about the others. That long action Ruger that I referred to is now a .257 AI with a Wiseman bbl. and a Bishop laminated and pillar bedded stock. He (my friend) insisted on that long action so he could seat the bullets out to the lands in the original .257 Rbts. I don't believe that the magazine had any kind of block in it to prevent that.

He could just as easily have chambered his new Wiseman bbl. to .25-06 if he had wanted to. But like a lot of us he is enamored with those AI's for the very reasons that have been discussed here so many times before.

Rev

reloaders nest site has got some loads listed for th 257 stw and a whole lot of other stuff I have a 257 stw put together just waiting for dies to make some brass and try it out probably more recoil than I will like but was curious about a 4000 fps plus bullet probably will not get much barrel life but also will rarely shoot it got to many projects going at once but have 3 22-259s and am thinking about that as an ai project later anybody got expeience with thar?

“If you really want a hot 25 go to 257 stw over 4000 fps with 100 gr bullet 0r 25-300 win mag 0ver 3800 with same bullet”

Kdub beat me to this one. Yes, if your building or buying a new rifle. The use of the Improved case shape allows the use of cartridges in actions such as the TC Contender when the original shape is not satisfactory.

“William, are you saying 60 f/s per EXTRA grain of powder in an AI case. If that is, indeed, what the rule is, then my experience matches almost perfectly.”

That’s not exactly what I intended to say but it sometimes works out this well – but not with every load combination and certainly as a result of higher operating pressure.

“ With 95-100 gr. bullets in my old 6mm Rem. bbl., I got 3000f/s with 43.0 grs. of IMR 4350. In my 6mm.”

That is a very efficient heat engine. Ken Howell pointed out once that operating above 60 fps per grain of powder often shortened case life and/or contributed to case stretching – he was not discussing Improved case shapes at the time. With regard to any cartridge I have not noticed reduced case life when operating 60 fpd per grain of powder or 30% efficiency. I have often noticed that right around this load level I have a very good compromise between velocity/energy and accuracy.

“AI in a new match bbl. I get 3150 or slightly more with a 95 gr. bullet and 45.5 grs. of IMR 4350. Those are not the same bbl. or even exactly the same length. Both were what I consider max safe loads. It's pretty close to your 60 f/s rule, if I'm reading it correctly.”

26% and 69 fps per grain of powder by my math and an efficient load.
Cartridge efficiency is just one of the varibles a handloader can use to establish starting and stopping points when working with new cartridges or powders for which there is no loading data. It is also one of the secondary items you can use to help establish where the balance point is between a specific powder charge, bullet weight, case shape and bore diameter. Graphing your chronograph results is also a good method for load development. Computer rograms such as RCBS Load are especially helpful for graphing loads by fps per grain of powder and these graphs will clearly demonstrate when a load combination “breaks over” on the graph and the fps per grain of powder increase drops or stops. With IMR powders this is easily graphed for most cartridges and provides the handloader with a clear indication of when adding more powder is not going to be of any signifcant advantage.

At least some modern .257 Rbts. came in a long actions (same length as the .30-06, etc.). I know the Ruger 77 came like that at one time, because my best friend and hunting buddy bought that Ruger 77 (long ago - maybe 1977?) just for that reason. . .

No doubt a lot of the guns can be converted. I should have been more clear: the .257 Roberts case cannot parent the longer STW case, because it isn't long enough. The AI's can all be blown out from their parent cases.

Highest efficiency is theoretically going to be a spherical case, just because that has the least surface area for its volume, and therefore presents the highest surface PSI for a given volume of gas squeezed into it. The result would optimize burning, but I can't figure out how to chamber and extract a sphere conveniently, without going back to the trapdoor Springfield design.

I have a NEF single shot .30-30 that I re chambered with an AI reamer. It shoots great. I didn't really need any more speed. I just wanted something different.

No doubt a lot of the guns can be converted. I should have been more clear: the .257 Roberts case cannot parent the longer STW case.......

Sorry, I'm a little thick headed sometimes. You meant the cartridge case , of course, not the rifle itself. I should have figured that out myself.

Rev

.
26% and 69 fps per grain of powder by my math and an efficient load.Cartridge efficiency is just one of the varibles a handloader can use to establish starting and stopping points when working with new cartridges or powders for which there is no loading data.......

Sorry to appear so dense. I realize that the % efficiency is the kinetic energy of the bullet at MV / the latent energy energy of the powder charge. What mathematical approach do you use to figure that? The % efficiency is new to me concerning firearms cartridges. I understand the 69 fps / gr. of powder. I can even figure the kinetic energy of the bullet easily enough. What I don't know is the latent energy in each gr. of that IMR 4350? Thanks for any info on this.

Rev