Came across this one today. Heard about it before, but didn't know someone had sorted out "Mach-5" loads for it! ;)

It's the 22-243 Middlestead. You can get 4,000fps+ and good accuracy, but still able to shoot relatively heavy 80gr bullets in a 10 twist barrel if you wish...

If you go to X-Light Custom (Berger 30gr) bullets, you can top over 5,000fps!!

ALL the loads are listed on this link below:

http://www.accuratereloading.com/22-243.html

http://www.accuratereloading.com/22243.jpg

"The following data was developed in a rifle build on the Hall BR action. The barrel was from Hart, stainless steel, # 6 and fluted. The chamber had a tight neck, of 0.246"

Federal 210M primers were used throughout our tests with the following loads. We also tried the Remington BR basic brass which came in 308 configuration and had a small primer pocket. We had to give up on that venture, as we had several rounds hang fire.

I think this is probably the largest 22-caliber case that can be used with currently available powders. We also tried a 6mm Remington necked down to 22-caliber, but were unable to get more velocity from it that this one. In fact, we found that to get roughly the same velocity – about 4000 fps – we had to use about 5.5 grains more of powder.

Looked at from a varminter’s point of view, this cartridge will give you about 100 fps more than the 220 Swift."

More: http://www.google.com/search?q=22-243+Middlestead&btnG=Google+Search&hl=en&lr=&ie=UTF-8&oe=UTF-8

Wonder what barrel life is like? That's a lot of powder capacity trying to get out of that .224 neck all at once!

'Course, if you can afford to build up something like this, guess barrel replacement is a minor consideration.

I know guys that won't walk out to get the paper in the morning if it's more than ten feet from the front door , we'll go to the moon and back for 100fps. I'm starting to believe my wife "I am sick"


444fitch

Depends on how you look at powder burn. At lewer velocity, all the molecules generated by the powder are going to "dink" off the bullet base, adding velocity....faster you go, the fewer molecules that are exceeding th speed of the bullet, so fewer of them "dink" off the base to add vel. Add to that that the faster molecules are also the smaller ones.

Burn enough powder, and there will be more fast molecules...proportion of fast vs. slow molecules stays the same, but by simply buring more powder, generate more of both types.

Pressure starts to climb though the roof quickly, and comes a limit where any more powder is just being pushed down the bore befor buring...so bullet vel. doesn't rise, but pressure do.

To do this trick, need a much longer powderburn/pressure curve. At a given pressure, the powder is going to have the same peak temperature (for the micro seconds of a powder burn, not much difference between pressure and temperature)... the only way to get more gas molecules "dinking" off the bullet base is to prolong the pressure by burning more powder...that's why a 55K .220 Swift load shoots faster than a 55K .223 load; same peak pressure, longer duration for the larger powder burn.

Remember the finger though the candle flame anaolgy of heat + temperature? The longer the powder burn, the more heat transfer to the metal, the shorter the barrel life.

Came across this one today. Heard about it before, but didn't know someone had sorted out "Mach-5" loads for it! ;)

It's the 22-243 Middlestead. You can get 4,000fps+ and good accuracy, but still able to shoot relatively heavy 80gr bullets in a 10 twist barrel if you wish...

If you go to X-Light Custom (Berger 30gr) bullets, you can top over 5,000fps!!

ALL the loads are listed on this link below:

http://www.accuratereloading.com/22-243.html

http://www.accuratereloading.com/22243.jpg

"The following data was developed in a rifle build on the Hall BR action. The barrel was from Hart, stainless steel, # 6 and fluted. The chamber had a tight neck, of 0.246"

Federal 210M primers were used throughout our tests with the following loads. We also tried the Remington BR basic brass which came in 308 configuration and had a small primer pocket. We had to give up on that venture, as we had several rounds hang fire.

I think this is probably the largest 22-caliber case that can be used with currently available powders. We also tried a 6mm Remington necked down to 22-caliber, but were unable to get more velocity from it that this one. In fact, we found that to get roughly the same velocity – about 4000 fps – we had to use about 5.5 grains more of powder.

Looked at from a varminter’s point of view, this cartridge will give you about 100 fps more than the 220 Swift."

More: http://www.google.com/search?q=22-243+Middlestead&btnG=Google+Search&hl=en&lr=&ie=UTF-8&oe=UTF-8


if you use gs custom hv bullets,you'd probably add, maybe 200 fps. of course they're 40 gr so probably wouldn't be faster.barrel life would probably be much longer.he has a 22-06 that shoots around 4700 and doesn't have much throat erosion at all after 2500 rounds.

another way to explain it: if the gasses from the powder expand at 4500 fps from the moment of ignition, but the bullet starts at 0 fps, the gasses are going to be building pressure until the bullet reaches 4500 fps. at that point the pressure built up behind the bullet will continue to push the bullet , even tho the peak pressure is going down at this point. now my theories have been getting shredded lately, so just consider the source.

monty

BTW i have a .25-.378 WBY (if i remember right) cartridge in my collection that i suspect was just necked down and stuffed with a bullet for a gag, but it has many years of patina on it. this would have been a screamer if it was authentic.

You arm chair physicists are way over complicating things here. As long as the force on the bottom of the bullet exceeds the forces of friction dragging the bullet (such as the barrel friction and the pressure built up in front of the bullet as it moves down the barrel) the bullet will continue to accelerate. The pressure can actually be going down in the chamber and the bullet will continue to accelerate as it goes down the barrel but at a decreasing rate of acceleration. Note that as long as acceleration is taking place, then the velocity of the bullet is increasing. To get the highest velocity, you need to keep the chamber pressure as high as possible without exceeding the guns limits for the duration that the bullet is traveling down the barrel. Keeping the bullet accelerating at the maximum safe rate results in the highest velocity upon exiting the barrel. It is all about pressure and not the speed of the gas which is behind the bullet. The speed of the gas behind the bullet is based on the pressure just as the speed of the bullet is based on the pressure. The speed of the gases has zero to do with the bullet speed - it is simply a result of pressure.

You want over 5000 fps - easy - get a .458 case necked down to .22 and a 6 foot barrel. With a slow burning powder that can maintain the chamber pressure , the bullet will continue to accelerate and reach extreme velocities.

The reason a .220 swift shoots faster than a 22-250 is that is has the ability to maintain a higher pressure (due to more powder burning ) over a longer duration as the bullet moves down the barrel. If that higher pressure is maintained for a longer duration, the bullet will go faster.

Who told you Gasses are only 4500fps? I think you're wrong and the guys who posted this on their website are right on this one. What evidence do you have to support the 4500fps theory on expanding gasses?

Sounds like a buncha' guesses and speculation to me.

TIA! ;)

Barrel would proably have to be over 6 feet in length before this amount of powder didn't show some rise in velocity. .22Rf will show a decrease in 16-20" of barrel, but it's only burning 3-4gr. of powder... frankly, am amazed it takes that much barrel to show a slow down.

Barrels of this kind of length would be a bit troublesome to carry arround.

I'm agreeing...believe bullets can be pushed to 5,000fps. Also believe wear to the barrel in doing so is going to be wicked. Great name, already used: 22 Earsplittingloundenboomer.

I found an interesting page here

"Aberdeen Proving Ground reached close to 9000 f/s using a .60 cal smooth bore gun and using 720 gr (!!) of IMR 4895 and a 113 gr projectile and they believed that the theoretical maximum velocity would be about 10,000 f/s."
Seems to be a credible source. The point he (the author)makes is that eventually the amount of powder(in gas form from burning) will exceed the bullet weight by enough that you don't get any more gains by adding more. I wonder how long the barrel was?

http://home.sprynet.com/~frfrog/miscellb.htm

Wow.... I though Roy Weatherby had done some experimenting for the U.S. Government way back when, and was reported to be pushing 5,000fps with some loads.

Certainly not something your average handloader would be dabbling with....

Gentlemen -

A good discussion topic and we're all interested in your opinions and whatever text references you may bring into it.

Let's please keep it civil, though. We can agree or disagree without getting huffy. Thank you.

Gentlemen -

A good discussion topic and we're all interested in your opinions and whatever text references you may bring into it.

Let's please keep it civil, though. We can agree or disagree without getting huffy. Thank you.


DEAR LONE STAR,
That's a long article to cite, but I read it and found it very interesting. It and other articles on the same website are also contradictory to your 4500fps expanding gasses.

"......This final expansion, coupled with the end of the friction between the projectile and the barrel, results in a final boost to the projectile so its maximum velocity is attained just beyond the muzzle (although "muzzle velocity" is usually measured at several metres past the muzzle anyway)......."

The author also cites projectiles that hit over 6,000fps.
"..........What is the maximum velocity which a projectile can be pushed to? This is ultimately limited by the expansion rate of the gas from the burning propellant. In rifles, the practical limit is around 1,200 m/s ( nearly 4,000 fps) achieved in small-calibre guns which only need light bullets (plus a couple of WW2 7.92mm anti-tank rifles). This is also about the maximum velocity for cannon firing conventional full-calibre HE shells. The highest velocities currently achieved are in tank guns firing APFSDS shot, which is extremely light for the caliber and allows velocities to be pushed up to 1,800 m/s (nearly 6,000 fps), which is close to the theoretical limit for conventional powder propellants. To go much faster would require a different technology. There is more on this subject in "In Search of High Velocity" on this website......"

I'm also aware of a long range competition rifle that was built around the 50BMG cartridge and necked down to .375". That Wildcat was called the "Mach 5" (topped 5000fps) and the projectiles were precision machined of solid brass or bronze (can't recall right now). They were considerably lighter than the standard jacketed 50 caliber rounds, and the designer suggested the brass or bronze bullets also exhibited a much lower friction inside the barrels.

Seems to be lotsa' examples of projectiles topping the average velocity of expanding gasses out there. I don't think they were all wrong or exagerations. For practical usefulness, I think it's over the top some. Tiny little bullets at hyper-velocity don't have much practical application in my World. I just thought it was interesting that someone had worked up multiple loads and documented everything on their web page to share with everyone...

In Search of High Velocity

http://www.quarry.nildram.co.uk/highvel.htm

On the page at the link above, the author cites another example of a projectile topping your theoretical 4500fps limit.

"...........It is probable that conventional chemistry has pushed muzzle velocities about as far as they can go; the rate of expansion of propellant gasses places a practical ceiling on muzzle velocity of around 6,000 fps............

..............smoothbore barrels were developed which also permitted a higher velocity due to less drag. The British have resisted this development because of the resulting loss of accuracy when firing HESH shells, so have retained rifled barrels. Instead, slip rings on the sabot are utilised to minimise the spin rate imparted to the FS projectile. However, 120-125mm smoothbore tank guns have now become standard, achieving muzzle velocities of up to 5,500 fps....."

5,500fps velocities now standard?


GOOD LUCK!

DEAR LONE STAR,
That's a long article to cite, but I read it and found it very interesting. It and other articles on the same website are also contradictory to your 4500fps expanding gasses.

"......This final expansion, coupled with the end of the friction between the projectile and the barrel, results in a final boost to the projectile so its maximum velocity is attained just beyond the muzzle (although "muzzle velocity" is usually measured at several metres past the muzzle anyway)......."

The author also cites projectiles that hit over 6,000fps if you missed that when you read the article.

"..........What is the maximum velocity which a projectile can be pushed to? This is ultimately limited by the expansion rate of the gas from the burning propellant. In rifles, the practical limit is around 1,200 m/s ( nearly 4,000 fps) achieved in small-calibre guns which only need light bullets (plus a couple of WW2 7.92mm anti-tank rifles). This is also about the maximum velocity for cannon firing conventional full-calibre HE shells. The highest velocities currently achieved are in tank guns firing APFSDS shot, which is extremely light for the caliber and allows velocities to be pushed up to 1,800 m/s (nearly 6,000 fps), which is close to the theoretical limit for conventional powder propellants. To go much faster would require a different technology. There is more on this subject in "In Search of High Velocity" on this website......"

I'm also aware of a long range competition rifle that was built around the 50BMG cartridge and necked down to .375". That Wildcat was called the "Mach 5" (topped 5000fps) and the projectiles were precision machined of solid brass or bronze (can't recall right now). They were considerably lighter than the standard jacketed 50 caliber rounds, and the designer suggested the brass or bronze bullets also exhibited a much lower friction inside the barrels.

Seems to be lotsa' examples of projectiles topping the average velocity of expanding gasses out there. I don't think they were all wrong or exagerations. For practical usefulness, I think it's over the top some. Tiny little bullets at hyper-velocity don't have much practical application in my World. I just thought it was interesting that someone had worked up multiple loads and documented everything on their web page to share with everyone...

In Search of High Velocity

http://www.quarry.nildram.co.uk/highvel.htm

On the page at the link above, the author cites another example of a projectile topping your theoretical 4500fps limit.

"...........It is probable that conventional chemistry has pushed muzzle velocities about as far as they can go; the rate of expansion of propellant gasses places a practical ceiling on muzzle velocity of around 6,000 fps............

..............smoothbore barrels were developed which also permitted a higher velocity due to less drag. The British have resisted this development because of the resulting loss of accuracy when firing HESH shells, so have retained rifled barrels. Instead, slip rings on the sabot are utilised to minimise the spin rate imparted to the FS projectile. However, 120-125mm smoothbore tank guns have now become standard, achieving muzzle velocities of up to 5,500 fps....."

5,500fps velocities now standard?


GOOD LUCK!

Gowge,

Yesterday, while working with the new 204 Ruger, one of my handloads delivered a chronographed 4281fps with a 32gr Hornady V-Max. I have a box of Berger 30gr 204 caliber bullets, and will be trying them out over the same powder charge. Don't know how close they will come to the mystical 4500fps, but is sort of interesting.

gunwriter

I read an article about testing procedures NASA uses to check the durability of coverings for space craft. They developed a gun that could shoot projectiles over 10,000 fps, and the propellent was ordinary gunpowder. This contraption was highly specialized, not a standard firearm by any means, but it leads me to believe that 5000 fps is possible in a sporting rifle.

As far as gas particles vs. pressure - I'm not a physicist, but I know that compressed air can cause a projectile to move over 2000 fps. That is an example I read about. I don't see how we can dismiss pressure as a factor. Interesting discussion, though.

I read an article about testing procedures NASA uses to check the durability of coverings for space craft. They developed a gun that could shoot projectiles over 10,000 fps, and the propellent was ordinary gunpowder. This contraption was highly specialized, not a standard firearm by any means, but it leads me to believe that 5000 fps is possible in a sporting rifle.

As far as gas particles vs. pressure - I'm not a physicist, but I know that compressed air can cause a projectile to move over 2000 fps. That is an example I read about. I don't see how we can dismiss pressure as a factor. Interesting discussion, though.


You must mean one of these 2 stage gas guns - this one is powered by gunpowder at Los Alamos - shoots projectiles 18,000 MPH(26,000 fps). Uses as much 3.5 Kilos(7.7 lbs) of gunpowder per shot.

http://www-phys.llnl.gov/Organization/HDivision/Research/GasGun/GasGun.html

who's huffy?

Wonder what barrel life is like? That's a lot of powder capacity trying to get out of that .224 neck all at once!

'Course, if you can afford to build up something like this, guess barrel replacement is a minor consideration.

I don't really have anything to add to this argument so I'll look at it from a different prospective.

Back in the mid 60's, we were strickly bowhunters, and with only recurve bows available, even the fastest bows were only capable of 180-200 FPS. Then came the compound and arrow speed went up about 40% with one simple principal, instead of the arrow de-celerating once it left the bow, now it accelerated with the action of the cam wheels. A simple idea that revolutionized the industry.

Seems to me that the bullet speed would be determined by the initial explosion in the case, and decelerate from there unless, the powder used would burn faster as it travels through the barrel.

I've shot a 25-06 that at night belched fire three feet from the muzzle. So, a lot of the powder burn did not help bullet speed at all.

I think the next big development in this industry would be
an accelerated powder that would actually burn faster as it travels the barrel. Bullets would accelerate and not decelerate.
Same principal, but probably short barrel life.
Is that too far fetched or should I just go take a nap?

Not far fetched but you would have to have an explosion of force to push the gasses forward. and then those gasses would have to expand in the barrel (just my thoughts)... interesting idea though...

I don't really have anything to add to this argument so I'll look at it from a different prospective.


Seems to me that the bullet speed would be determined by the initial explosion in the case, and decelerate from there unless, the powder used would burn faster as it travels through the barrel.

I think the next big development in this industry would be
an accelerated powder that would actually burn faster as it travels the barrel. Bullets would accelerate and not decelerate.
Same principal, but probably short barrel life.
Is that too far fetched or should I just go take a nap?


Actually the bullet does continue accelerate down the length of the barrel. The bullet goes faster and faster as it moves down the barrel. What happens is not really an explosion but a fast burn of the powder. The higher the pressure then usually the faster the powder will burn. Slow burning powders are actually better in large cases because as the bullet travels down the barrel, the powder continues to generate pressure driving the bullet down the barrel. Don't think of it as a shove from an initial explosion then drag down the barrel. Ideally the pressure will peak very quick and remain at the peak while the bullet accelerates down the barrel. This is why longer barrels generate more velocity.

just wondering. Can you mix poweders? like lets say i mix a fast and slow burning powder figuring that a fast start and then a slower one to push the bullet more while its in the barrel. this make sence?

Saw the Weatherby reference in a previous post - here is a link to the Weatherby site describing how they used a 30-378 Weatherby shooting a 30 gr bullet to exceed 5000 fps. The Weatherby article claims some wildcatters made 6000 but is not specific as to who or how.

http://www.weatherby.com/notes/velocity.shtml

That 4,500FPS may well be close to the average...but would that limit a projectile to that speed? IF it's average, then wouldn't part f the gas exceed that figure, and part of the gas be below that?

Using current rifle tech., would need a big case run at 55,000PSI to generate a massive amount of gas pressure. ALL of the gas pressure would exert a push on the bullet at ignition, and as the bullet's velocity increased, less and less of it would add push. Past 4,500fps, less than 1/2 the gas produced would be used in pushing the bullet (for this, we'll ignore other energy drains like heat, vibration, and noise), but if you start ut with enough total gas, then 1/2 of "a lot" is still enough to accelerate a bullet.

The alternative is to run higher pressures in smaller cases. That has problems.

Rifle makers like safety margins...who doesn't?...so building a rifle to stand 80,000PSI on a standard basis would probably require an ultimate strength of 120,000-150,000PSI. Kind of hard to get brass cases to work at this level; perhaps a little research into other materials would be in order.

Barrels don't live happy at this kind of pressure...pressure and temperature are pretty much the same thing in this kind of time frame). Erosion of the barrel would be fast. Think that could be beaten with beter alloys that currently exist. Some work has been done with chamber liners in somemachinegun barrels to combat the effects of heat...is some experimental work being done with specail alloys of steel and even ceramics. Unfortunatley, those alloys don't allow easy rifling and have some other drawbacks in machining.

just wondering. Can you mix poweders? like lets say i mix a fast and slow burning powder figuring that a fast start and then a slower one to push the bullet more while its in the barrel. this make sence?

I think you are onto something - the reason slow powder works better is it is the best fit for maintining a high pressure curve. If you flip flop what you said though - have a slow powder that then speeds up in rate that would fit even better. As the bullet accelerates, you need more and more gas at a faster rate to fill in the chamber and barrel behind the bullet and keep pressure high. Perhaps a coating on the powder that retards the burning slightly - say 10% then increases in rate. That would do a better job of maintaining peak pressure diring the firing.

The big problem with the 4500 fps number is that it's an Average, measured indirectly. There may be ways to measure the gas velocity now, but there weren't a century ago when all of this was worked out. So they measured everything else, including the recoil, and calculated the unknown component, gas velocity.

From Hatcher's Notebook, page 288.
Practical Methods of Approximating Recoil Due to Muzzle Blast
In view of the extreme difficulty of writing a completely accurate mathematical formula that will be practical for use in everyday calculations to obtain that part of the recoil due to muzzle blast, most authorities use some approximation that gives results agreeing reasonably well with those found by actual dynamometer tests.
One approach to the problem is to consider that the gas when freed by the exit of the bullet starts to expand at a rate that is determined by the pressure and density conditions existing in the bore at that time, and that this rate falls to zero as the gas reaches atmospheric pressure. It has been considered that for modern rifles with pressures in the range of the ordinary military rifle of the past several decades, the gas starts to expand with a velocity of some 9000 feet per second, and that the rate falls to zero rapidly, with an average value of 4700 feet per second. Bevis and Donovan, in The Modern Rifle, 1917, state that experiments with a Siebert Velocimeter lead to the conclusion that a value of 4700 may be used for the exit velocity of the gases. Balleisen, in Principles of Firearms, 1945, gives the same figure.

For high powered rifles, this seems to give results that are satisfactorily close to measured values. For shotguns, it is much too high. For ultra high velocity rifles, it is most likely too low.

This figure of 4700 feet per second as the average effective velocity of the powder gases includes both the motion of the gases along the bore before the bullet leaves, and the sudden expansion to atmospheric pressure after the bullet makes its exit. Using this figure, we may now write an equation that will give us a good practical approximation to the total recoil velocity, including all three of the elements discussed above. If all weights are expressed in pounds, this formula would be:
V = wv + 4700 c .......................... (c)
............. W
End Quote

Now since a number of guns have reached 5000 fps, it's obvious that the gas has to reach a much higher velocity or it would stop pushing.

Consider that the gas is stuck behind a slow moving bullet until the bullet clears the barrel, then it has to accelerate to whatever velocity it reaches while the barrel pressure in dropping. As noted above, the gas likely reaches a higher velocity in an ultra high velocity gun, as it's going faster when it reaches the muzzle.

Here's a couple of tricks that speed things up besides stuffing more powder in the case. One is an oxygen deficit powder, so we have light carbon monoxide molecules pushing faster than the heavier CO2 can. This applies to the oxides of hydrogen and nitrogen too, as well as the free radials. Of course we get a nice fireball when these hot molecules get out of the barrel and find some atmospheric oxygen.

Another trick is a multiple perf powder, although it's only practical with bigger guns. The big naval guns use a 7 hole powder kernel, so the burning surface increases until the 88% point. Compare that to an uncoated ball powder that starts out with a bang and ends with a whimper.

A recent experiment with the infamous .22-378 Ergensplittin Loudenboomer got 5079 fps with a 40 grain Ballistic Tip and a 118 grains of VV 170. (Precision Shooting, Feb. 1999)

Bye
Jack

Well said, Jack. Amen!!!

LoneStar -

A gentle rejoiner was given earlier for everyone to debate or comment in a civil manner.

Your sarcasm has been duly noted - it has no place on this forum. Future postings of like nature will either be edited for content or deleted as imflammatory remarks adding nothing to the discussion matter.

kdub
Moderator

Gowge,

Yesterday, while working with the new 204 Ruger, one of my handloads delivered a chronographed 4281fps with a 32gr Hornady V-Max. I have a box of Berger 30gr 204 caliber bullets, and will be trying them out over the same powder charge. Don't know how close they will come to the mystical 4500fps, but is sort of interesting.

gunwriter


Gunwriter, those Berger Bullets must be really special. Look forward to hearing how they work out for you.

GOOD LUCK! ;)

You accepted the source I offered as legitimate - then you changed the subject to include esoteric military weapon systems as "proof" that you were right all along. In fact, your original contention is, and was, incorrect, and you are apparently not man enough to admit it. We can agree to disagree here, but my respect for your powers of debate are now.....nonexistant. Sorry.:(

Lonestar,

While this forum encourages the discussion of differing opinion regarding ballistic theories and practices, it is also to be a factual discussion. You, sir have crossed the line with a personal attack to one member's character. Your opinions are your own regarding any person's character, and you are invited to keep them such, or lamentably be banned from these forums.

Good Day,

Marshall Stanton
Owner, Beartooth Bullets & ShootersForum.com

Gentlemen,
I edited a couple of the posts in this thread because of the derogitory, condescending tone. This is not a place in which you can attack or belittle other posters. Lonestar - please notice I was able to leave all of the pertinent firearm-related data in your post, without the presence of putdowns. I could say the same for other posters, too. This is not a contest or a debate. It is a place to share ideas. There are either no winners, as when threads deteriorate into spittin' matches, or we are all winners, when threads give us a good deal of information to think over.
kdub already mentioned civility before. No more of the "debate" garbage. Post your ideas and opinions about the subject, not other posters.

Question someone would perhaps like to discuss- would this not be a perfect "problem" that could be solved by using a solid(one piece) propellant with a variable burn rate? Rather than a grandular powder which essentially slows down the burn rate as it is consumed? This would allow for a engineering a variable burn rate that is slow at first then faster. If I remember correctly, solid rocket engines (even models)have this technology in use today.

Hmmmm.........

Yes, interesting question.

Not being schooled in physics past 101, always thought solid rocket propellent had just one burn rate that was requlated by the shape of the propellent as packed into the rocket body. Maybe it does have differing layers of differing burn rates, I just don't know.

It would be possible to coat a stick powder with a veriable retardant in the body length - not sure how this would be accomplished with ball powder, though. Even the stick would present a multitude of manufacturing problems.

Your thoughts of the rocket brings up an analogy to my simple understanding of projectile acceleration. Realizing as the rocket traverses increasingly thinner layers of atmosphere and the friction becomes less drag, still and all, a rocket continues ever increasing acceleration with the given thrust of the propellent. Same could be said of a bullet being forced down the path of least resistance (bore). The initial release from the case neck, then engagement of the rifling take the biggest effort, therefore increasing chamber pressure unseats the projectile to overcome these friction causing items. Once the bullet has been engraved, the friction (drag) is increasingly less with each increment of bore travel. The steadily building of pressure caused by the burning propellent and expanding heat/gas will fill the void left by the departing projectile and continue building behind the projectile (as the gasses expand far more rapidly than the expanding free bore space behind the bullet grows) to provide energy to increase the speed of the bullet until finally departing the muzzle and a huge pressure drop occurs as the gasses may expand in a large unrestricted enviroment.

All this to say, The bullet gains momentum all the way to the muzzle due to expanding propellent. If you can find means to continue the burn of the propellent while contained in the chamber and bore space, the speed continues to increase until released at the muzzle, providing there is not excessive drag (friction) due to too great a length of barrel.

I believe Gibbs was chasing some of these principles when he was working on the front ignition loading techniques. This involed a flash tube that ran from the flash hole up to close to the base of the bullet. This was supposed to start the fire at the front and burn backwards, so to speak into the charge, with slow powder out front changing to a faster powder back near the base. I believe he was trying to make just the cartridge the combustion chamber rather than the cartridge and the whole barrel. As AZshooter brought to thought, a computer controlled loading station could adjust in a charge,(after a learning curve) that would bring up the pressure rapidly but not peaky , as is common to firearms now, then run out of fuel to burn before the bullet reaches the end of the barrel to reduce muzzle flash. maintaining a high pressure throughout most of the barrel. Part of what Gibbs was trying to do was to keep the powder from blowing down the barrel and acting as a sand blasting agent on the throat and barrel. A front ignition with a controlled burn rate/time ,as in a solid charge , would seem to solve a few problems. Might be the stove is a little too warm and I'm just full of hot air......

hi guys,
ive been following the discussion a bit. lively! i'm hardly a compressible flow expert, but my college thermo book has graphs for AIR reaching velocities of 11k+ fps (Mach 10) to find useful constants. i imagine more volitale gases can do better. [that statement is made with no knowledge of the conditions modern firearms are restricted to in terms of combustion]. in the world of the college engineer, venturi shaped pipes are used to generate high velocity gas flow. can you imagine your rifle barrel with a necked down section? picture the bullet flying across the necked expanse to contact matching rifling on the other side but with increase pressure provided by the necked down section. TURBO boost, or a deadly rupture? sorry about the rambling. carry on.

josie

On a couple of other unrelated threads, I made mention of reading the Germans developed an anti-tank cannon in WWII for use against the Russians that had a tapered bore. The projectile had a skirt that would compress and engrave the reducing bore rifling. The expanding gasses propelling the slug down the bore had an ever smaller object to push against. Again, faulty memory indicates the projectile skirt was something on the order of 100mm and ended up exiting at 50mm or so.

Wish I could recall the name of the cannon and the exiting muzzle velocity of the round. Anyway, it served the desired purpose - was a great T-34 and Joseph Stalin heavy tank killer due to the extreme muzzle velocity.

On a couple of other unrelated threads, I made mention of reading the Germans developed an anti-tank cannon in WWII for use against the Russians that had a tapered bore. The projectile had a skirt that would compress and engrave the reducing bore rifling. The expanding gasses propelling the slug down the bore had an ever smaller object to push against. Again, faulty memory indicates the projectile skirt was something on the order of 100mm and ended up exiting at 50mm or so.......


A.P.S.V. - Armour Piercing Squeezed Velocity

A solid tungsten core with steel shims. Originally a German design, squeeze bore shells were also developed for the British 2 pdr. gun using the Littlejohn Adaptor. Upon firing, the tapered bore of the Panzerbüchse 41 squeezed the shell down from its original diameter of 28 mm to only 20 mm, resulting in a velocity of 4,600 feet per second -- the highest velocity in WW2 by a margin of 1,500 feet per second. The Panzerbüchse 41 had a maximum penetration of 94 mm at 100 metres. The weapon was small and lightweight, making it ideal for Fallschirmjäger operations.

http://miniatures.de/html/pzgr/shelltypes.html

Lotsa' hits on Google! ;)

http://www.google.com/search?sourceid=navclient&ie=UTF-8&oe=UTF-8&q=German+tapered+bore+anti%2Dtank+gun

kdub, i don't agree with your description of chamber pressure vs. position of bullet in the barrel.the peak pressure is realized getting the bullet engraved into the rifling using conventional full groove diameter bullets.banded type bullets don't see maximum pressure until it moves a couple of inches or so.once the bullet starts moving,the pressure starts dropping until it exits the muzzle.most guns with 55-60k have about 20k when the bullet exits.all the powders we use burn way to fast in their unaltered state.that's why retardants are put on them to slow down the burn rate.each peice of powder has retardant on approx. 25% from the surface.the problem is there's always much more surface area to start out with.once the powder has burned through the retardant,it starts burning at a much faster rate.this helps compensate for the rapidly expanding combustion chamber.but it's still not enough.the pressure "peaks" getting the bullet started and continues to fall off as the bullet moves down the barrel

This Cartridge Sounds Like The Old 220 Weatherby Rocket As Far As Velocity Goes. I Just Read About It In Rifle Magazine. According To It You Can Beat The 220 Swift By 100 Fps Or More Safely Through A 26" Barrel.

Wondering about that falling pressure as bullet travels down bore. Has anyone ever expermented with a duplex charge , say , a slightly faster powder for the last 10~15 % of charge??

That's why they have horse races, Deerhunterdave - everyone is entitled to their opinion.

I can't help but think we've both said the same thing in your first sentence, though.

kdub, i guess my interpretation of what you said a couple posts above was wrong.you said, steadily increasing of pressure and building pressure.the way i'm reading it,you're making it sound like the pressure continues to build until the bullet exits the barrel.i don't think we're saying the same thing.

Well, let's see if I can clarify -

The most chamber pressure (peak) is required to unseat the bullet from the cartridge neck, ram it into the rifling for engraving and get the bullet on its way down the barrel.

Once the bullet has accepted the engraving and is traveling down bore, the less effort is required of the propelling gasses to continue its journey.

Now, if as you say (for arguments sake) the gasses no longer build and begin decay there is less push to the bullet base. so the bullet has to be slowing down, due to loss of acceleration.

That leaves the conundrum of longer barrels developing higher velocities than short barrels. If the gasses had expanded to their fullest capacity just after overcoming the resistance of leaving the case and hitting the rifling, then the best velocity would be attained in a barrel that was just an inch or so in length.

With the exception of a .22LR round (and possibly other rimfire cartridges) which has developed its maximum velocity in a 18 1/2" barrel, all others develop maximum velocity in a 28"-30" barrel. Most "magnum" cartridges are chambered in 26" tubes as the longest one that hunters find practical for field use. When shortening to the standard 22" - 24" barrels, there is normally a 25-30 fps velocity loss per inch from the 26". Further shortening continues the velocity loss per inch.

Along with the velocity loss, the attendant muzzle blast increases the shorter the barrel. This is due to powder still being converted to gas. Sometimes, there are unburned powder kernals recovered downrange of a short barreled firearm.

Now, this to me indicates there is still gas being developed in the bore as the bullet travels down it. If new gas is being introduced, the pressure will still be building faster than additional expansion chamber is being provided. If the bullet develops maximum velocity downbore from the peak pressure point, there has to be additional propellent to continue overcoming the drag friction encountered in the journey.

Just my uneducated thoughts on it.

powder is still being converted to gas after the bullet has engreved in the rifling,yes. but,the farther the bullet moves down the barrel,the lower the pressure gets.20,000 psi at the end of the barrel is still accelerating the bullet.i once talked to a ballistician that studied this stuff for NASA.he told me there was no appreciable gain in velocity after the bullet traveled 6"

powder is still being converted to gas after the bullet has engreved in the rifling,yes. but,the farther the bullet moves down the barrel,the lower the pressure gets.20,000 psi at the end of the barrel is still accelerating the bullet.i once talked to a ballistician that studied this stuff for NASA.he told me there was no appreciable gain in velocity after the bullet traveled 6"

So then how do you account for the gain of velocity in longer barrels? as long as the gasses are still produced the pressure should get the gasses moving fast enough for the bullet to accelerate.

longer barrels produce higher velocities because of the time it's being pushed.i've never said that the bullet slows down.as the bullet moves down the barrel,the pressure continually falls.the bullet is still accelerating because the pressure is enough to make it go faster. if the pressure increased as the bullet moves,more velocity would be achieved in the second half of the barrel.i can assure you this is not the case.what is the velocity gain of a 30" barrel compared to a 20. maybe 500-600 fps?it's because the rate of acceleration is decreasing.i didn't say velocity decreases.the velocity is still increasing as it goes down the barrel,but not as much as the begining of the barrel because the pressure is continually dropping as the bullet travels down the bore.
please e-mail me your phone # and i will gladly call you at your convenience.

Even the .22RF's tiny little 3 - 4gr charge shows vel. gains out to 18-20". Think the 6" figure may be for peak pressure, whicih does occur early...but so long as the driving pressure is worth more than friction, it's going to accelerate. Does gain less per inch of barrel as the barrel gets longer, but it still gains (at least with any round as large or larger than the .22Hornt).

(At least black powder seems to gain vel. as a percentage of length change. Becasue a 4" change to a 20" barrel is a larger percentage of barrel length than a 4" change to a 30" barrel, the gain per inch is higher when adding length to the short tube than to the long tube).

Can get bad data from comparing differnt barrels to eache other...too many variables. And as we can't weld sections onto the end of a short barrel, pretty much have to use a long barrel and lop off sections to get data shot through the dame chamber/bore.

Ah, now i understand Dave.THAT makes sence, i thought you were saying that it doesn't accelerate after 6" thank you for clarifying.

ribbonstone,i was comparing the velocity of a 30 and 20" barrel. not adding 4" to either.the velocity gain of a 50% longer barrel only produces maybe 20% more speed.it's because the pressure keeps falling as the bullet moves down the barrel.also,peak pressure is getting the bullet engraved in the rifling, not 6" downbore.
i thought the way i was arguing with you guys,we might as well be married!

Think I'll have to reasearch that a bit...don't bleive all barrle reach their peak at engravement...may be, but I'd have to take a look at some of the big case/slow poweder rounds to see it that works out. Reguardless, peak pressure is early..and even if only getting 20% (and I think in real life, wthout a load change, it would be more like 12%)for a move from 20" to 30", that's still an impressive amount for "free" (free in that it doesn't increase peak presure one bit).

i agree,it's probably closer to 12,i just threw a high number out to try and make my point.originally,everyone was saying the pressure kept increasing until it left the barrel,i was trying to come up with an explanation that would clarify this.

I believe you are right R.S. about peak pressure having a little room to show up at. On one of the other forums I was reading about some peak pressure differences between the short/fat cartridges as compared to a long tapered conventional caartridge with slow powder. Turbulence within the case and the short strong flame front seems to be part of what makes a s/f case more effiecent, but also , some feel, it makes them prone to rather quick peaky pressures. Wheras , with a stretch case , more of the powder may be down the bore before the fire catches up to it, slightly stretching out the pressure curve a bit. In working with other fuels and combustion process, (not gun related) I have seen where heated fuels and open combustion chambers with strong flame fronts can make for explosive conditions. Taking a wild flying guess that this may be something similiar.