Reason long barreled guns produce greater velocity
Forum rules
Welcome to the Leverguns.Com General Discussions Forum. This is a high-class place so act respectable. We discuss most anything here other than politics... politely.
Please post political post in the new Politics forum.
Welcome to the Leverguns.Com General Discussions Forum. This is a high-class place so act respectable. We discuss most anything here other than politics... politely.
Please post political post in the new Politics forum.
Reason long barreled guns produce greater velocity
Seems I am forever reading posts about how long barrels produce more velocity because there is more time for the powder to burn.
My rhetorical question is if one has two airguns exactly alike except that one has a 6" barrel and the other a 20" barrel does the longer one produce higher velocities because the compressed air/ CO2 has more time to burn?
My rhetorical question is if one has two airguns exactly alike except that one has a 6" barrel and the other a 20" barrel does the longer one produce higher velocities because the compressed air/ CO2 has more time to burn?
-
- Shootist
- Posts: 1682
- Joined: Sun Dec 09, 2007 7:46 pm
- Location: BLACK HILLS, DAKOTA TERRITORY
- sore shoulder
- Advanced Levergunner
- Posts: 2611
- Joined: Sat Sep 15, 2007 4:51 pm
- Location: 9000ft in the Rockies
-
- Advanced Levergunner
- Posts: 6972
- Joined: Tue Apr 03, 2007 8:52 pm
- Location: Ridgefield WA. USA
There is a point of diminishing returns where more length is of no advantage and will actually slow the bullet down.
Since the air rifle bullet,like the powder driven bullet, starts from a dead stop,it takes time and barrel length to get to full velocity. any barrel length over the point of full velocity just slows the bullet back down some. Each powder has a different point where this happens.
Since the air rifle bullet,like the powder driven bullet, starts from a dead stop,it takes time and barrel length to get to full velocity. any barrel length over the point of full velocity just slows the bullet back down some. Each powder has a different point where this happens.
sore shoulder wrote:No, because the compressed air is not burning, rather it is constantly depressurizing in the barrel as the space behind the projectile increases. In a firearm the burning powder is keeping pressure behind the projectile.
In a firearm all the powder that is going to burn so has done so in the first 5-6 inches. After that the pressure drops steadily all along... just like in an air rifle.
-
- Levergunner 2.0
- Posts: 235
- Joined: Tue Dec 18, 2007 2:51 pm
- Location: Sandy, Utah
In any firearm the bullet will continue to accelerate so long as the gas pressure exerted against the base of the bullet exceeds the force necessary to overcome friction of the bullet in the bore. This is true no matter how the pressure is derived. There is a balance point, having mostly to do with the expansion ratio of the chamber/bore, after which the bullet will begin to decelerate due to friction with the bore surface. This varies from about 12" for .22 Short, 16" for Long Rifle up to the muzzle for most calibers. Most centerfires would reach the balance point, if an infinite length barrel were possible, somewhare beyond the muzzle. For air or CO2 powered guns the balance point is shorter even than in the 22s, probably in the8-10" area.
-
- Levergunner 2.0
- Posts: 124
- Joined: Mon Dec 17, 2007 7:36 pm
- Location: Sunny, Arizona
That is incorrect!BAGTIC wrote: In a firearm all the powder that is going to burn so has done so in the first 5-6 inches. After that the pressure drops steadily all along... just like in an air rifle.
Take a slow burning powder like RL-21 in a rifle and it burns the length of the barrel. Shorten the barrel and it will continue to burn after it has left the barrel (though NOT helping in velocity) But makes a large muzzle flash as the powder burns.
Now take a fast burning like Bullseye and you are correct it is done burning in a pistol caliber in just several inches.
Re: Reason long barreled guns produce greater velocity
If your logic was right, a contender with a .223 super 14 barrel, and a 223 varminter with a 24 inch barrel would get the same velocity with the same loads. Fact of the matter is they don't.BAGTIC wrote:Seems I am forever reading posts about how long barrels produce more velocity because there is more time for the powder to burn.
My rhetorical question is if one has two airguns exactly alike except that one has a 6" barrel and the other a 20" barrel does the longer one produce higher velocities because the compressed air/ CO2 has more time to burn?
Depending on the powder being used there is a point at which the difference between a 18 -20 inch barrel and a 24-26 inch barrel isn't anything to get excited about ,but there is a difference..
I've also found the same as Pete.
With the Aguila Super Colibri (primer only)
Out of a 16" 615fps
out of a 20" 590fps
out of a 23" 580fps
The longer the barrel the more the pressure diminishes and friction takes over.
Now when using 2400 / H110 / Lil'gun there is a definite increase in Velocity between shorter and longer barrrels.
With the Aguila Super Colibri (primer only)
Out of a 16" 615fps
out of a 20" 590fps
out of a 23" 580fps
The longer the barrel the more the pressure diminishes and friction takes over.
Now when using 2400 / H110 / Lil'gun there is a definite increase in Velocity between shorter and longer barrrels.
Even the compressed air need to escape the barrel.....the velocity stops increasing when the barrel is vented to atmosphear (the bullet leaves).
The Rotten Fruit Always Hits The Ground First
Proud Life Member Of:
NRA
Second Amendment Foundation
Citizens Committee For The Right To Keep And Bear Arms
DAV
Proud Life Member Of:
NRA
Second Amendment Foundation
Citizens Committee For The Right To Keep And Bear Arms
DAV
- KirkD
- Desktop Artiste
- Posts: 4406
- Joined: Sat Apr 07, 2007 6:52 am
- Location: Central Ontario, Canada
- Contact:
As the bullet moves down the barrel the pressure drops. As long as the force exerted by the pressure is greater than the friction force between the bullet and the bore, the bullet will continue to accelerate.
When the bullet gets far enough down the barrel such that the force exerted by the pressure is less than the friction force between the bullet and the barrel, the bullet will begin to slow down.
Where that point is depends upon the amount of powder, type of bullet, etc. Certainly, no one can deny that most pistol bullets have a higher muzzle velocity out of a 20" rifle barrel than they do out of a 3" pistol barrel.
When the bullet gets far enough down the barrel such that the force exerted by the pressure is less than the friction force between the bullet and the barrel, the bullet will begin to slow down.
Where that point is depends upon the amount of powder, type of bullet, etc. Certainly, no one can deny that most pistol bullets have a higher muzzle velocity out of a 20" rifle barrel than they do out of a 3" pistol barrel.
-
- Levergunner 2.0
- Posts: 237
- Joined: Mon Sep 03, 2007 7:37 pm
- Location: Indiana
Mostly true. However, it is not as simple as it sounds. If it were simply pressure = velocity, a load that stretched a gun to near the point of a blowup might wreck the gun, but it would fire a terribly fast bullet.
Does it? Think about it!
Isn't "if" a grand word?
Does it? Think about it!
Isn't "if" a grand word?
Pastordon
Pastordon's Blog
The man who thinks he knows something does not yet know as he ought to know. (1 Cor. 8:2)
Pastordon's Blog
The man who thinks he knows something does not yet know as he ought to know. (1 Cor. 8:2)
I have seen instances where 2 guns of the same type (different barrel lengths)were shot at the same time using the same ammo and the shorter of the 2 actually had a higher velocity.
Many factors affect velocity. Chamber dimensions and throating being 2 of them. Some powders produce pretty much the same velocity in an 18" barrel as they do in a 26" barrel.
At any rate long barrels just aren't worth the extra effort/pain. In a lever gun anything over 22" is just because you like it. I personally prefer the 18" barrels.
100fps isn't enough to matter on game.
Many factors affect velocity. Chamber dimensions and throating being 2 of them. Some powders produce pretty much the same velocity in an 18" barrel as they do in a 26" barrel.
At any rate long barrels just aren't worth the extra effort/pain. In a lever gun anything over 22" is just because you like it. I personally prefer the 18" barrels.
100fps isn't enough to matter on game.
"I have reached up to the gun rack and taken down the .30/30 carbine by some process of natural selection, not condoned perhaps by many experts but easily explained by those who spend long periods in the wilderness areas."~Calvin Rutstrum~
"You come to the swamp, you better leave your skirt at the house"~Dave Canterbury~
"You come to the swamp, you better leave your skirt at the house"~Dave Canterbury~
A rifle needs a scope. Sight radius is a moot point when you use one. Fighting all that muzzle weight is a major problem for me. I think 22"s is perfect.
"I have reached up to the gun rack and taken down the .30/30 carbine by some process of natural selection, not condoned perhaps by many experts but easily explained by those who spend long periods in the wilderness areas."~Calvin Rutstrum~
"You come to the swamp, you better leave your skirt at the house"~Dave Canterbury~
"You come to the swamp, you better leave your skirt at the house"~Dave Canterbury~
-
- Levergunner 3.0
- Posts: 739
- Joined: Mon Dec 17, 2007 3:40 pm
- Location: utah
Black powder years ago needed longer barrels. Probley another thing looked at back then was in levers some people might like the longer magazine tubes on longer barrels. How about some of those old cheap "long tom" shotguns that some people thought they needed!
Kind of the same thinking my dad had in the 50s. We wanted to get into bow hunting. Dad was a very strong athletic 6 ft 5". So he went and found a used 95 pound bow!! He soon bought a new 65 pounder!
Kind of the same thinking my dad had in the 50s. We wanted to get into bow hunting. Dad was a very strong athletic 6 ft 5". So he went and found a used 95 pound bow!! He soon bought a new 65 pounder!