How Does Barrel Length Affect Overall Power?

mrerick · 08-14-2017, 06:11 PM

There are a number of dynamic forces involved in firearms ballistics from ignition through terminal energy transfer.

The gliding surface of a bullet against the rifling and side of the barrel certainly encounters friction all the time it's traveling down a barrel. As long powder continues burning and creating gas while the bullet still plugs the end of things, the bullet will accelerate. For most loads, the longer the barrel, the faster the projectile exits the muzzle of the barrel. This also increases the amount of terminal energy transferred by the bullet.

The size of the powder load and the burning speed of the powder determines whether it continues to burn while the bullet travels down the barrel. If it's not complete by the time the bullet exits the barrel, you get muzzle flash in clear air behind the bullet.

There are, of course, other forces at work. There is some resistance involved in the bullet exiting the cartridge case, and more involved when the bullet has jumped the air gap and starts engaging the rifling, biting into the lands. From that moment, considerable friction expends heat as the bullet bearing surface glides down the barrel. Pistol ammunition for 9mm Luger generates just under 35,000. More for NATO and +P.

Marc

08-14-2017, 06:11 PM	#3
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,924 Thanks: 1,377 Thanked 3,136 Times in 1,519 Posts	There are a number of dynamic forces involved in firearms ballistics from ignition through terminal energy transfer. The gliding surface of a bullet against the rifling and side of the barrel certainly encounters friction all the time it's traveling down a barrel. As long powder continues burning and creating gas while the bullet still plugs the end of things, the bullet will accelerate. For most loads, the longer the barrel, the faster the projectile exits the muzzle of the barrel. This also increases the amount of terminal energy transferred by the bullet. The size of the powder load and the burning speed of the powder determines whether it continues to burn while the bullet travels down the barrel. If it's not complete by the time the bullet exits the barrel, you get muzzle flash in clear air behind the bullet. There are, of course, other forces at work. There is some resistance involved in the bullet exiting the cartridge case, and more involved when the bullet has jumped the air gap and starts engaging the rifling, biting into the lands. From that moment, considerable friction expends heat as the bullet bearing surface glides down the barrel. Pistol ammunition for 9mm Luger generates just under 35,000. More for NATO and +P. Marc __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.