I've been told that every caliber handgun has an optimum or ideal barrel length, meaning the barrel length where the powder burn inside the barrel still propels the bullet faster than the friction caused by additional barrel length slows it down. (I guess it also must depend to some degree on the particular bullet weight; powder charge, etc.) But is there a general guideline? For example, I seem to remember that many years ago when Iwas a kid, highway patrolmen in my state carried Colt O.P. 38 Specials with 6" barrels because they were supposed to be a lot more powerful than shorter barreled versions. It would be interesting (to me anyway) to see what the optimum barrel lengths are for all the main pistol and revolver calibers. Is there anywhere to go to get that info? Does anybody on the forum know? Thanks in advance for any help on this.
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Optimum barrel lengths?
- Thread starter DG45
- Start date
For most pistol ammunition, I would expect that the optimum barrel length would approach or be in rifle barrel territory. 9x19, 45acp, 357mag and 44mag all see significant performance increases out of 16" barrel carbines, compared to handguns. I seem to remember reading that the optimum barrel length for 22lr was about 12" to 14".
Actuality, I wouldn't limit you ststement to every caliber. More accurately, every cartridge "recipe" has its own optimum barrel length.
Actuality, I wouldn't limit you ststement to every caliber. More accurately, every cartridge "recipe" has its own optimum barrel length.
Magnum Wheel Man
New member
there is a huge variance in powder burn rates... some can fully burn all the powder in 6" of barrel, other could be in rifle length barrels... also case shape ( straight wall, or bottleneck ), case capacity, bullet weight, & primer type all can make a difference... I'm sure there is a calculatable length of diminishing returns, but there would be more variable than just the caliber
The powder has finished deflagration within a few inches of barrel travel, and for some handgun calibers and fast powders before the bullet even clears the case.
The remainder of the barrel time is spent with the expanding gases continuing to push the bullet and a continuously dropping pressure, b ut still well above sliding friction.
Only very small cases (.22 RF) will run out of pressure in a reassonable barrel (~16-18 inches for a .22 LR).
The remainder of the barrel time is spent with the expanding gases continuing to push the bullet and a continuously dropping pressure, b ut still well above sliding friction.
Only very small cases (.22 RF) will run out of pressure in a reassonable barrel (~16-18 inches for a .22 LR).
Firepower!
New member
I like 3" in revolver but cant find in Pakistan.
I have to settle for 4"
I have to settle for 4"
Many pistol cartridges do get higher velocity in carbine barrels than they do in normal pistol length barrels.
But the 45 ACP may not be one of them. I get higher velocities with 6" and 7" barrels than I do with 5" barrels with the 45 ACP, but actually get lower velocities with 16" barrels.
In conventional rifle cartridges I start getting negative marginal returns somewhere between 38" and 40" of barrel length.
Working on a 80" barrel to see how it does.
.
But the 45 ACP may not be one of them. I get higher velocities with 6" and 7" barrels than I do with 5" barrels with the 45 ACP, but actually get lower velocities with 16" barrels.
In conventional rifle cartridges I start getting negative marginal returns somewhere between 38" and 40" of barrel length.
Working on a 80" barrel to see how it does.
.
The Ballistics by the inch project has a mind-numbing amount if data, although the ammo choices were typically factory defensive ammo. Click Results, then the caliber.
Lee
Lee
re: "Ballastics by the Inch" data
Thanks to all who've replied so far; especially to Imccrock for the hyperlink to "Ballistics By The Inch". That's very informative stuff; although all firing appears to have been done using Thompson contender as a platform. I think that's a single barrel pistol isn't it? If, so, then the results of these tests are probably reliable for automatic pistol cartridges, and probably accurately indicates the "potential" velocity of a particular revolver cartridge, but in actual practice, revolvers lose some of their potential power due to the gas loss between the cylinder and barrel. That would not have occurred using a Thompson Contender single barrel. So, I doubt whether in the real world, when fired from a revolver, whether rounds such as 357 and 38 Special would achieve nearly the velocities shown in these tests. (Incidentally, the 38 Special cartridges they reported using in these tests were actually 38 Special +P rounds; not standard velocity 38 Special cartridges. Misidentifying 38 Special +P ammo as 38 Special ammo is potentially dangerous.) I'd love to see some standard 38 Special data for a change. I've got an old Colt Police Positive Special made in 1930 that I'm scared to shoot +P ammo in.
Thanks to all who've replied so far; especially to Imccrock for the hyperlink to "Ballistics By The Inch". That's very informative stuff; although all firing appears to have been done using Thompson contender as a platform. I think that's a single barrel pistol isn't it? If, so, then the results of these tests are probably reliable for automatic pistol cartridges, and probably accurately indicates the "potential" velocity of a particular revolver cartridge, but in actual practice, revolvers lose some of their potential power due to the gas loss between the cylinder and barrel. That would not have occurred using a Thompson Contender single barrel. So, I doubt whether in the real world, when fired from a revolver, whether rounds such as 357 and 38 Special would achieve nearly the velocities shown in these tests. (Incidentally, the 38 Special cartridges they reported using in these tests were actually 38 Special +P rounds; not standard velocity 38 Special cartridges. Misidentifying 38 Special +P ammo as 38 Special ammo is potentially dangerous.) I'd love to see some standard 38 Special data for a change. I've got an old Colt Police Positive Special made in 1930 that I'm scared to shoot +P ammo in.
You lose a little to the barrel/cylinder gap. You gain a little back because revolver barrels are measured from the forcing cone forward while semi-auto barrels (and TC barrels) are measured from the breech forward.
The numbers are probably representative for any pistol type.
The numbers are probably representative for any pistol type.
I doubt whether in the real world, when fired from a revolver, whether rounds such as 357 and 38 Special would achieve nearly the velocities shown in these tests.
They won't. But does it really matter. Longer barrels will yield more velocity that shorter ones. Bigger bores are not as prone to velocity loss as smaller ones. Those are the only real rules. Powders and primers can make a world of differences in the same barrel length. No "normal" revolver will have enough barrel to get near "optimal" length so don't worry about it ;-)
38 Special (+P) 2 inch vs. 6 inch barrels
My math is always suspect, but if the tables in "Ballistics By The Inch" are correct, a +P 125 grain Federal Hydra Shock fired from a 2 inch 38 Special barrel has 1/3 less potential velocity than the same round would have if fired from a 6 inch barrel. That would result in a significant loss of bullet energy to spend on the target too. I know there are concealment reasons to own a snub nose 38 Special. I was watching TV when Jack Ruby shot Lee Harvey Oswald so I know that 38 Special snubbies CAN be devastatingly lethal one shot stoppers. (But gee, that was a perfectly placed round, wasn't it? Fired upward inside the rib cage from point blank range on the left side of the abdomen. Tore up everything. Oswald said "Ow! it hurts", went down, lost consciousness immediately and never woke up or spoke another word . Lucky shot? Anybody know what kind of round that was? I read everything I could find about it, but I never learned that.) But I digress. My point is that if you're buying a 38 Special for home defense, a 6" barrel will give you a LOT more power than a 2".
My math is always suspect, but if the tables in "Ballistics By The Inch" are correct, a +P 125 grain Federal Hydra Shock fired from a 2 inch 38 Special barrel has 1/3 less potential velocity than the same round would have if fired from a 6 inch barrel. That would result in a significant loss of bullet energy to spend on the target too. I know there are concealment reasons to own a snub nose 38 Special. I was watching TV when Jack Ruby shot Lee Harvey Oswald so I know that 38 Special snubbies CAN be devastatingly lethal one shot stoppers. (But gee, that was a perfectly placed round, wasn't it? Fired upward inside the rib cage from point blank range on the left side of the abdomen. Tore up everything. Oswald said "Ow! it hurts", went down, lost consciousness immediately and never woke up or spoke another word . Lucky shot? Anybody know what kind of round that was? I read everything I could find about it, but I never learned that.) But I digress. My point is that if you're buying a 38 Special for home defense, a 6" barrel will give you a LOT more power than a 2".
One thing we fail to take into account is powder. You need to adjust your powder choice to the barrel lenght you use and its attended purposes.
Notice most agree that the 45 ACP dosn't very as much as say the 44 mag. Maybe its because the 45 ACP is normally loaded with faster burning powder, i.e. Bullseye or 231. Whereas the 44 mag is loaded with slower burning powder such as 2400 or 296.
So pick you gun for its attended purposes, then adjust you load to suit your choice of barrel lenght.
Example, I load 231 in my 642, I tested the load where I get less muzzle flash and the most velocity (safetly). Of course you cant get rid of all the muzzle flash but you need to do testing to reach a happy medium between muzzle flash and velocity with your chosen bullet.
My Model 29 has a 6 in barrel. I want slower powder, so I do the same testing to reach my goal in my model 29.
Same with all my pistols and rifles. I shoot high power with a 22 inch barrel in 308. Makes no since to have a slow burning powder such as 4831 that wont burn in my 22 in barrel, so I go to a med burning powder like 4895.
But I have a couple 1000 yard rifles that have 26 to 29 in barrels, I use slower powder in them.
A good example is the M21 (NM M14 Sniper system). The M14 has a 22 inch barrel. The normal load (special ball M118) is loaded (or was at that time) with 42 grns of 4895. Snipers some times shoot at night so in sniper school we did night firing. You step back from the rifle in the dark, and there is ZERO muzzle flash. The 2550 FPS Velocity, from 4895, the 22 in barrel is the perfect combination for this gun. The Army spent a lot of money figuring this out but we can do simular testing with our guns a bit cheaper.
All guns are differant, as is the requirments of all guns. Dont get hung unp on barrel lenth. You want a short barreled pistol to fit in your pocket, get one, the develope the load to fit your gun and use.
Factory bullets are designed to shoot in everything, but dont work in everything. Thats why you find very few sucessful target shooters, rifle or pistol who dont reload.
Notice most agree that the 45 ACP dosn't very as much as say the 44 mag. Maybe its because the 45 ACP is normally loaded with faster burning powder, i.e. Bullseye or 231. Whereas the 44 mag is loaded with slower burning powder such as 2400 or 296.
So pick you gun for its attended purposes, then adjust you load to suit your choice of barrel lenght.
Example, I load 231 in my 642, I tested the load where I get less muzzle flash and the most velocity (safetly). Of course you cant get rid of all the muzzle flash but you need to do testing to reach a happy medium between muzzle flash and velocity with your chosen bullet.
My Model 29 has a 6 in barrel. I want slower powder, so I do the same testing to reach my goal in my model 29.
Same with all my pistols and rifles. I shoot high power with a 22 inch barrel in 308. Makes no since to have a slow burning powder such as 4831 that wont burn in my 22 in barrel, so I go to a med burning powder like 4895.
But I have a couple 1000 yard rifles that have 26 to 29 in barrels, I use slower powder in them.
A good example is the M21 (NM M14 Sniper system). The M14 has a 22 inch barrel. The normal load (special ball M118) is loaded (or was at that time) with 42 grns of 4895. Snipers some times shoot at night so in sniper school we did night firing. You step back from the rifle in the dark, and there is ZERO muzzle flash. The 2550 FPS Velocity, from 4895, the 22 in barrel is the perfect combination for this gun. The Army spent a lot of money figuring this out but we can do simular testing with our guns a bit cheaper.
All guns are differant, as is the requirments of all guns. Dont get hung unp on barrel lenth. You want a short barreled pistol to fit in your pocket, get one, the develope the load to fit your gun and use.
Factory bullets are designed to shoot in everything, but dont work in everything. Thats why you find very few sucessful target shooters, rifle or pistol who dont reload.