Firearm Barrel Length

Why do longer barrels give greater accuracy? I have an idea, but let me hear what you think (or know).

Originally posted by AThousandYoung
Why do longer barrels give greater accuracy? I have an idea, but let me hear what you think (or know).

I suppose if the barrel is rifled along most of its length, you will impart a greater spin to the bullet with a longer barrel, since the barrel can only impart spin to the bullet while the two are in contact. The spin will stabilize the bullet's path due to conservation of angular momentum.

Originally posted by PBE6
I suppose if the barrel is rifled along most of its length, you will impart a greater spin to the bullet with a longer barrel, since the barrel can only impart spin to the bullet while the two are in contact. The spin will stabilize the bullet's path due to conservation of angular momentum.

My suspicion is that the longer barrel gives one two widely separated points to line up with the target.

That's just a wild guess though. I haven't looked into it.

Originally posted by PBE6
I suppose if the barrel is rifled along most of its length, you will impart a greater spin to the bullet with a longer barrel, since the barrel can only impart spin to the bullet while the two are in contact. The spin will stabilize the bullet's path due to conservation of angular momentum.

I believe you are correct, but when did they begin to rifle barrels? In the colonial age, muskets with longer barrels were more accurate than pistols, so the length of the barrel might actually be directly related to accuracy, aside from the the rifling.

Kentucky Rifle, or long rifle, has many names, was around during the revulotionary war. took 4 times longer to load since you had to jam the lead ball down the barrel while a smooth barrel rolled down. However it had 3 x the range. range and accuracy were basically considered the same back in the day. they were used but the revulotionary war was, for the most part, lining up in rows and opening fire at about 50 yards from the enemy, along with bayonet charges, so the slow loading rifle was not in favor as men were shoulder to shoulder so speed was the key not accuracy.

but yes, longer the barrel, more the spin, greater the accuracy.

example i guess would be throwing a football. more spin = increased range and accuracy

Originally posted by Drew L
Kentucky Rifle, or long rifle, has many names, was around during the revulotionary war. took 4 times longer to load since you had to jam the lead ball down the barrel while a smooth barrel rolled down. However it had 3 x the range. range and accuracy were basically considered the same back in the day. they were used but the revulotionary war was, for the most ...[text shortened]... uracy.

example i guess would be throwing a football. more spin = increased range and accuracy

But the spin is determined by the design of the rifling of the barrel, not the length. The bullet engages the rifling. It doesn't rip through it. Does it?

Originally posted by AThousandYoung
But the spin is determined by the design of the rifling of the barrel, not the length. The bullet engages the rifling. It doesn't rip through it. Does it?

yes it does engage the rifling. However the lead ball is traveling rather quickly [not sure of the fps] , by maximizing the length of the barrel it puts the greatest amount of spin on the lead ball.

lets say and 8 year old throws a football, he isn't that strong and his arm is short, so it has a spin on it but it isn't that great and the ball goes to the left a little ways due to his lack of power, spin, and aim. [musket] a pro quarterback then throws it with much more force and being 6'1'' his arm is much longer, thus the spin is greater and it stays on target [rifle]

hope that clears things up

Originally posted by Drew L
yes it does engage the rifling. However the lead ball is traveling rather quickly [not sure of the fps] , by maximizing the length of the barrel it puts the greatest amount of spin on the lead ball.

lets say and 8 year old throws a football, he isn't that strong and his arm is short, so it has a spin on it but it isn't that great and the ball goes to the l ...[text shortened]... nger, thus the spin is greater and it stays on target [rifle]

hope that clears things up

Terrible analogy. The "strength" of the bullet comes from the amount of powder, and the reason extra arm length helps with throwing is that it has a greater moment arm. This requires the projectile to leave at a right angle to the arm, while in a gun the projectile comes out the end.

Here we go - I looked it up.

Rifles had long barrels, usually over 4 feet, in order for the black powder to have more time to burn therefore increasing velocity and thus accuracy/range

Muskets weren't accurate to begin with so they [the british] found that by shortening the barrel from around 62 inches to 46 or so had little affect on the accuracy but made them much easier to handle in bayonet charges.


Sorry, I should have looked everything up first.

the rifle I used to look up the above information was the Long Rifle;
the musket was the Britsih Brown Bess, both used during the Revolutionary war.

Originally posted by AThousandYoung
Terrible analogy. The "strength" of the bullet comes from the amount of powder, and the reason extra arm length helps with throwing is that it has a greater moment arm. This requires the projectile to leave at a right angle to the arm, while in a gun the projectile comes out the end.

your right, bad analogy, but best I could come up with on the spot.

actually, thinking on it, I can't come up with a good analogy.

A relevant post:

snub nosed .357's kind of suck. The barrel is too short to allow the cartridge to get the velocity that is it's entire reason for existing. A 2 1/2 inch barrel in any magnum cartidge is just a lot of muzzle flash , looks neat, but it's barely more powerful than a .38 special out of a longer barrel. Shoot it in the dark and you'll be deaf and flash blinded for several seconds, an important consideration for a home defense gun.
Check the velocity figures of .357 magnum loads from snubbies, you'll be horrified, that gun/load configuration is not anywhere near as powerful as you think. Why choose a snubby for home defense to begin with, they're meant for concealed carry.

http://www.playtheimmortalgame.com/board/showthread.php?threadid=74726&page=4

Looks like the barrel length does influence bullet velocity, at least according to that guy.