I have seen various posts about barrel length in relation to muzzle velocity and muzzle energy. Most generally, the discussions say longer barrel, more "punch", but I saw a post (not sure if it was this forum) that a guy with a 16" 22LR that chrono'd faster and was harder hitting than 20" or 24" 22LR barrels. It seems to make since that a 22 would start slowing down in a longer barrel because of the powder all being burnt before the bullet exits. Of course, this would be affected by the powder loads, but I was wondering if any testing has been done on different calibers to figure out what optimum barrel length for each caliber would be?

This barrel length would depend on what ammo you would be using and what the speed was. I know that most .22 bench guns have a barrel length of about 20". That is with ammo going about 1050fps. Faster ammo like CCI mini mags I would think would do better in a longer barrel. I am not 100% on this, but just makes sense to me. Main thing is the speed of the ammo you want to use. Would be nice to have an old barrel to test. If I had one this is one test I would like to know what that magic length is.

Just a thought, was that other post you saw talking about just best speed, or accuracy? I would want a length that was the most accurate, not the fastest.

This barrel length would depend on what ammo you would be using and what the speed was. I know that most .22 bench guns have a barrel length of about 20". That is with ammo going about 1050fps. Faster ammo like CCI mini mags I would think would do better in a longer barrel. I am not 100% on this, but just makes sense to me. Main thing is the speed of the ammo you want to use. Would be nice to have an old barrel to test. If I had one this is one test I would like to know what that magic length is.

Just a thought, was that other post you saw talking about just best speed, or accuracy? I would want a length that was the most accurate, not the fastest.


Someone with their copy of Hatcher's Notebook might look it up...but remember that his estimation of a 30-06 (and this was with the faster powders used in the 1930's and 40's) wouldn't stop shoing a gain in velcoity until the barrle was somthinglike 3 yards long.

The .22LR burns somthing like 1.8gr.- 2.2gr. of powder...it takes 16" of barrel for this tiny cahrge to peak out.

Waht isn't fair is comparing differnt barrels...wuld need ONE barrel, really long, cut back in seps to get meaningful data. I've had identical lengths (22") give widely differing velocity readings with the same ammo.


"Magic" length? Max. vel. does not have to equate to max. accuracy.

I have seen various posts about barrel length in relation to muzzle velocity and muzzle energy. Most generally, the discussions say longer barrel, more "punch", but I saw a post (not sure if it was this forum) that a guy with a 16" 22LR that chrono'd faster and was harder hitting than 20" or 24" 22LR barrels. It seems to make since that a 22 would start slowing down in a longer barrel because of the powder all being burnt before the bullet exits. Of course, this would be affected by the powder loads, but I was wondering if any testing has been done on different calibers to figure out what optimum barrel length for each caliber would be?


Even if the powder is all spent, you still have a great amount of pressure behind the projectile. Remember, powder burning creates pressure, the air expands and that pressure pushes the projectile. That is the reason that reloaders control the pressure by using powders that burn at different rates. I guess it is possible that a shorter barrel could produce faster velousities, but 16 to 20 inches the 20 should produce better velousity. As far as the best for each caliber, I beleive you loose about 100 FPS for each inch a barrel is shortened, as a generic number. I hunt w/ some 24", some 22", and some 18" barrels. I can bet you the game does not know the difference. Shoot what you are comfortable with. There is no best in anything when it comes to most firearms. JP

I was going to be a smart @$$ and say "27' but it's not very practical".... but I see Ribbonstone once again beat me to it...only he's serious....now that's the scary part! LOL

Was going to buy a .375 H&H one time w/ a 34" barrel. Very good accuracy, didn't chrono it but the POI with my handloads was exactly 2" higher at 200 yds than the factory loads...same difference from the 26" barrel one I already had. Definitely not scientific but if there was any velocity gain from the extra barrel length, it wasn't showing any on the POI.

Remember he also calculated the weight of the breech block needed for a blow back 30-06...but don't remember the exact weight (other than it was more than you'd care to carry around).

Do belive that velocity will show as gain until the point where bullet friction's value is greater than gas expansion. When comparing differnt rifle barrels, would have to have the same friction value...which is darned hard to figure out.


But therre should be a "ball park" figure out there for cases burning 30gr. of pwoder or more. I prefer to figure the following:

Velocity will increase or decrease by something between 1/3 and 1/2 the PERCENTAGE of length change.


Why the percentage?

Adding 2" to a 20" barrel has more vel. value than adding 2" to a 33" barrel.

Would guess that making a new ball-park-estimator using barrel volume would be more impressive...but i can't work those out in my head like I can with just lengths (and as volume and length would be proportional, don;'t guess it matters much).

Hatcher only lists 4 barrel lengths.

24" = 2700

32" = 2848

It is a common sense thing. At any given bore dia., the more case volume the longer the bbl need to maximize the velocity. Example 308 Win will max about 20 to 22 inchs, the 300 RUM will max about 26 to 30 inches. ;)

Hatcher only lists 4 barrel lengths.

24" = 2700

32" = 2848

Thanks...don't remember what book I read it in (and the books are gone) be belive it was one of Hatcher's.

Still, think the idea here is that there shuld be a gain in velocity long after you've past the reasonable length for human carry.

But you do not. You are forgeting the friction between the bullet and the bbl.
I recall a test with 4 different 308 Win loads and a bbl starting at 26" and cut back a 1" segments. Average velocity CAME UP from 26" to 24" then changed very little from 24" to 22", showed a slight drop from 22" to 20" and moderate drop from 20" to 18". :eek:

But you do not. You are forgeting the friction between the bullet and the bbl.
I recall a test with 4 different 308 Win loads and a bbl starting at 26" and cut back a 1" segments. Average velocity CAME UP from 26" to 24" then changed very little from 24" to 22", showed a slight drop from 22" to 20" and moderate drop from 20" to 18". :eek:

Yea, that is the kind of info I am looking for. As pointed out before, It has to be done with one barrel with 1 load and would be different in a different barrel with a different load, I know. But it would give you a ballpark to look for.

This was a test done several years ago by the late (Great) Bob Melik (SP) and it was very informative.

Have been several tests of this type, problem being that none of them seem to be in total agreement. That should be expected as barrels seldome agree about loads.

Think the important things from all the tests I've seen are that:

1. different loads (becasue of the differnt powders used) vary more or less with barrel length.

2. the vel. gains past a certain point, while still there, are minor.

3. IN GENERAL, the more powder being burned, the more effective a long barrel.

4. that there seems to be at least 5variables at work: powder charge, barrel volume, friction,pressure generated, and powder burning speed.

Agree with ribbonstone, particularily the last (#4) item.

All these variables must be considered when trying to determine optimum velocity for a particular cartridge.

The old military rifles had barrels of 28" to 32" with this aspect in mind. I've got several what I consider "high performance" rifles that have 27" barrels for the purpose of wringing out as much velocity as possible for the given cartridge. Wouldn't want to try using them in thick brush type hunting, but they aren't too awkward stand hunting or out here in the open West.

Isn't a slightly shorter barrel also more likely to be accurate, as the harmonics of the barrel play with shorter barrels less than longer barrels? I believe most rifle and barrel manufacturers have given us the best compromise, the magic length is 22-26"

I've found that if I use an average of roughly 50 fps it seems to be fairly close in most of my rifles. I think optimal may be different for different calibers and I couldn't tell you what makes that difference. For the 270 Win for instance, I think optimal is 24". Both Ken Waters and Jack O'Connor found that there was 100+ fps gain over a 22" barrel. A thread on another forum talked about this a while back also:

http://www.thehunterslife.com/forums/showthread.php?t=3050

According to this very interesting article -----> http://www.marlinowners.com/board/viewtopic.php?t=11886

The magic length for accuracy is 21 3/4".

Agree with ribbonstone, particularily the last (#4) item.

All these variables must be considered when trying to determine optimum velocity for a particular cartridge.

The old military rifles had barrels of 28" to 32" with this aspect in mind. I've got several what I consider "high performance" rifles that have 27" barrels for the purpose of wringing out as much velocity as possible for the given cartridge. Wouldn't want to try using them in thick brush type hunting, but they aren't too awkward stand hunting or out here in the open West.


I've been wondering about that.

Didn't find a whole bunch of short barrled muzzle loaders...but they managed to sneak through the woods and hunt with those 40" - 44"full stocked long guns or the 28-32" Hawken types. Oddly, the later plains/Hawken types rifles (wee there isn't much bursh) were shorter than the earlier long rifles (used mostly in th woods).

You'd have expected the opposite, at least by today's standards.

After a few seasons of bow hunting, come to realize ANY rifle gets through the woods better than a bow.

Isn't a slightly shorter barrel also more likely to be accurate, as the harmonics of the barrel play with shorter barrels less than longer barrels? I believe most rifle and barrel manufacturers have given us the best compromise, the magic length is 22-26"


Now that brings up a very important, and valid point. Barrel Harmonics! What does that mean? Well ( for you younger guys and others) when a gunsmith was making barrels he would finish the barrel, but not to finished length. The barrel w/ action attached was then fitted to a vise (action only). A plate of glass was then layed over the barrel and covered w/ a light coat of very fine sand. When it was fired, a pattern would be visible on the sand. Where the pattern intersected the barrel were the points of best accuracy. Varying the thickness of the steel will effect where the lines intersect the barrel. I have some very old books that touch on this technique. Now they use computers. Sorry, just wanted to add this. Did not mean to rant! JB could explain it better, it is the same as the vibration of a Guitar string. JP

According to this very interesting article -----> http://www.marlinowners.com/board/viewtopic.php?t=11886

The magic length for accuracy is 21 3/4".

That article is talking about the 22PPC. I believe he is wanting to know about the .22LR barrel length.

Never mind. My mistake. He is wanting info on different calibers as well.

"Didn't find a whole bunch of short barrled muzzle loaders...but they managed to sneak through the woods and hunt with those 40" - 44"full stocked long guns or the 28-32" Hawken types. Oddly, the later plains/Hawken types rifles (wee there isn't much bursh) were shorter than the earlier long rifles (used mostly in th woods).

You'd have expected the opposite, at least by today's standards."

Muzzle loaders do find a significant ballistic advantage in longer barrels. Plus, I suspect that when you only had one shot and iron sights, the accuracy advantages of a longer barrel outweighed the handiness aspect. Remember too that traditional muzzle-loaders have "zero length" actions - keeping the overall length a bit more reasonable. I suspect that the stouter/shorter Hawkens became more popular as more folks took to carrying a rifle on horseback (where a very long barrel would be awkward).

M1, Great thread. Thanks! I really enjoyed it.

Gismo, I read that one a while back. very interesting. wouldn't we all just LOVE to have a 300+ yd "tunnel" to target practice in?

You all talking about the muzzle loaders and old long guns are hitting on what brought this question to my mind in the first place! Great discussion! Thanks for everyone's input.

Shorter barrels tend to be thicker and more stiff. Not as prone to whipping around like a longer, slender barrel will. Harmonics can be controlled as witness the BOSS system on Brownings/Winchesters and the various aftermarket systems that are available. Que is a good one that is both a brake and barrel tuner.

Shorter barrels tend to be thicker and more stiff. Not as prone to whipping around like a longer, slender barrel will.

As far as I know, that is harmonics... correct me if I'm wrong... :)

I love to read threads like this! It makes me think!
My thought now is that "we" are "backwords thinking".
Should we be tuning the barrel for the load, or tuning the load for the barrel? Perhaps the answer is somewhere in the middle?
I have seen some rifles perform "magic" with some loads, and shoot crap with others. Handloaders play with this all the time. Most do not alter barrel lengh to do it. They alter bullet weight or powder burn rate to find the "sweet spot" that the rifle likes.
If we could alter the burn rate of smokless powder in a controlled manor we might be able to shoot good with any length barrel?
Thanks for a good read.
Cheezywan

It is not the barrel length as such that makes the difference, it is the expansion ratio (inverse of compression ratio). All the powder is burned in first inch or so of bullet travel. After that it is the expansion of the high pressure gas that accelerates the bullet. No different than an air rifle. The cartridge is merely a convenient source of high pressure gas.

Just for fun:

http://www.accuratereloading.com/223sb.html

Yeah, I know it's not a .22
But fun anyway.

From that it looks like about any barrel length works for accuracy. Just different loads to get it there. Not much of a difference though.

Bagtic, where did you get the info about powder buring up in the first inch of bullet travel? I want to read that. Never heard that one before.

I'm with Gismo as that'd be an interesting read. I was under the impression that some (if not most or all) of muzzle flash was powder burning as it came out the muzzle. I've seen bigger muzzle flash on heavier loads so I'm sure some of that is burning powder.

It is not the barrel length as such that makes the difference, it is the expansion ratio (inverse of compression ratio). All the powder is burned in first inch or so of bullet travel. After that it is the expansion of the high pressure gas that accelerates the bullet. No different than an air rifle. The cartridge is merely a convenient source of high pressure gas.
When I was overseas, we used to take the flash suppressor off of our M60 machine guns for night operations. When you pulled the trigger, it would belch fire out three ft from the muzzle. It always looked fierce, so we did it.
I'm not that technical, but there was something burning inside of those barrels which were about 20-22" in length.
Also, since it takes fuel, heat and oxygen to make fire, seems to me that when that fuel (powder) and heat hit that oxygen at the end of the barrel, we get an added explosion or a continuation of the initial one. I know that there is probably some oxygen in the barrel but not as much as when it escapes.

Anyway, I agree with everybody!

Now that brings up a very important, and valid point. Barrel Harmonics! What does that mean? Well ( for you younger guys and others) when a gunsmith was making barrels he would finish the barrel, but not to finished length. The barrel w/ action attached was then fitted to a vise (action only). A plate of glass was then layed over the barrel and covered w/ a light coat of very fine sand. When it was fired, a pattern would be visible on the sand. Where the pattern intersected the barrel were the points of best accuracy. Varying the thickness of the steel will effect where the lines intersect the barrel. I have some very old books that touch on this technique. Now they use computers. Sorry, just wanted to add this. Did not mean to rant! JB could explain it better, it is the same as the vibration of a Guitar string. JP

It sounds like the gunsmiths were finding nodes, and it seems to me that cutting the barrel would change the placement of those nodes, since changing the length of a vibrating body changes the frequency. For instance, with guitar strings the pitch depends on the length, girth, and tension of the wire; or so I seem to remember. So again, changing the length of a barrel would (one would think) change the harmonics of it.

Interesting topic. :)