Understanding barrel lengths and accuracy
- Thread starter Matt
- Start date
Most reloading manuals from Speer, Hornady, Sierra and others have sections on the effect of barrel length on velocity. With some high intensity rifle cartridges it can be as much as 100fps/inch.
Accuracy is not affected by barrel length, only by barrel quality. For guns with open/iron sights, barrel length helps improve "practical" accuracy by providing a longer sight radius but the shorter barrels are just a "mechanically" accurate as the longer ones.
Mikey
Accuracy is not affected by barrel length, only by barrel quality. For guns with open/iron sights, barrel length helps improve "practical" accuracy by providing a longer sight radius but the shorter barrels are just a "mechanically" accurate as the longer ones.
Mikey
Art Eatman
Staff in Memoriam
To add a bit to Mikey's comments: Most of the published data for muzzle velocity & energy is from a 26" barrel.
Wile it varies from cartridge to cartridge, a rule of thumb is a loss of from 60 ft/sec to 100 ft/sec per inch of barrel less than 26".
It is my understanding--and I could be wrong--that cartridges such as the .308 and the .243 suffer less than, say, the .30-'06. The reason seems to be the width vs. length relationship of the case. Extrapolating from this, then, it would seem that in general a Short Fat Fannie sort of cartridge case would have less velocity loss than a Long Lanky Louise...
(You're on your own, now, Bubba.)
I vaguely recall an article in the Rifleman discussing testing where a 30" barrel produced no notable gain in velocity over a 26" barrel.
Having nothing to do with your question: Short barrels are LOUDer...
In the FWIW department, shifting to pistols, an experiment with a 44 Maggie started with a 10" or so barrel. The usual results occurred, for each inch of reduction. The final chronograph, just for fun, was with the barrel unscrewed from the revolver. The "muzzle" velocity through the chrono with a 240-grain bullet was around 1,100 ft/sec. Barrel? Who needs barrels?
, Art
Wile it varies from cartridge to cartridge, a rule of thumb is a loss of from 60 ft/sec to 100 ft/sec per inch of barrel less than 26".
It is my understanding--and I could be wrong--that cartridges such as the .308 and the .243 suffer less than, say, the .30-'06. The reason seems to be the width vs. length relationship of the case. Extrapolating from this, then, it would seem that in general a Short Fat Fannie sort of cartridge case would have less velocity loss than a Long Lanky Louise...
(You're on your own, now, Bubba.)I vaguely recall an article in the Rifleman discussing testing where a 30" barrel produced no notable gain in velocity over a 26" barrel.
Having nothing to do with your question: Short barrels are LOUDer...
In the FWIW department, shifting to pistols, an experiment with a 44 Maggie started with a 10" or so barrel. The usual results occurred, for each inch of reduction. The final chronograph, just for fun, was with the barrel unscrewed from the revolver. The "muzzle" velocity through the chrono with a 240-grain bullet was around 1,100 ft/sec. Barrel? Who needs barrels?
, Art
Danger Dave
New member
Where can I get me one of those 30 ft barrels? I got a shotgun that needs just a little more reach....
Actually, I'm not too surprised about the results. With a small cartridge like the .32, the powder would burn up quickly and not continue to force the bullet to accelerate down the full length of the barrel. The volume in the barrel behind the bullet increases as the bullet traveled down the barrel, but the gasses have stopped expanding faster than the bullet is travelling away from them. Then, friction becomes the governing force and the bullet slows down. Also, I think it's possible that if the gasses can no fill the volume behind the bullet, it would create a vacuum effect, slowing the bullet down even more.
Just my thoughts...
Actually, I'm not too surprised about the results. With a small cartridge like the .32, the powder would burn up quickly and not continue to force the bullet to accelerate down the full length of the barrel. The volume in the barrel behind the bullet increases as the bullet traveled down the barrel, but the gasses have stopped expanding faster than the bullet is travelling away from them. Then, friction becomes the governing force and the bullet slows down. Also, I think it's possible that if the gasses can no fill the volume behind the bullet, it would create a vacuum effect, slowing the bullet down even more.
Just my thoughts...
Art Eatman
Staff in Memoriam
Hey, thanks, DC. You just restored my faith in my memory.
Art
Art
And without ANY barrel you have a "pepperbox revolver". As a kid, I read a "science" fiction book about a land inhabited by upright-walking alligators. Those beasts were armed with large caliber pepperboxes and hand grenades...the author had made a point that these were far superior to shotguns available to humans in the same area.
Just what kind of tech limitations would produce a set-up where pepperboxes and double-barreled shotguns would co-exist with elevators, telephones and not much in the way of any transportation? Maybe I am reading too much into kiddie books...
Just what kind of tech limitations would produce a set-up where pepperboxes and double-barreled shotguns would co-exist with elevators, telephones and not much in the way of any transportation? Maybe I am reading too much into kiddie books...