Thernlund
Member
I saw this thread and did a Google search for some long barrels. Then I started thinking...
I wonder how long a barrel would have to be before the bullet would not be able to exit the end? This would certainly depend on the cartridge no question. I imagine it would also depend on the type of action. For example, a revolver has a flash gap that will allow pressure to escape faster than and auto would, etc.
So thinking about this, I think the main factors would be the bullet's friction on the barrel, the charge behind it, and how fast the gases could escape. As well, the area inside the barrel behind the bullet as it moved away from the chamber would factor.
I did some quick math. If the chamber and the bullet created perfectly sealed space between them, a .45ACP would travel 682' down a barrel of infinite length before the pressure reached below 2 psi. It would likely stop before that from friction. I used 21,000 psi as the chamber pressure and assumed that pressure would be halved as the distance from the chamber doubled (1", 2", 4", 8", etc).
Dumb thought experiments, I know. I once asked how physically long an Ethernet pack was (about 100km from a T1 as it happens).
Comments?
-T.
I wonder how long a barrel would have to be before the bullet would not be able to exit the end? This would certainly depend on the cartridge no question. I imagine it would also depend on the type of action. For example, a revolver has a flash gap that will allow pressure to escape faster than and auto would, etc.
So thinking about this, I think the main factors would be the bullet's friction on the barrel, the charge behind it, and how fast the gases could escape. As well, the area inside the barrel behind the bullet as it moved away from the chamber would factor.
I did some quick math. If the chamber and the bullet created perfectly sealed space between them, a .45ACP would travel 682' down a barrel of infinite length before the pressure reached below 2 psi. It would likely stop before that from friction. I used 21,000 psi as the chamber pressure and assumed that pressure would be halved as the distance from the chamber doubled (1", 2", 4", 8", etc).
Dumb thought experiments, I know. I once asked how physically long an Ethernet pack was (about 100km from a T1 as it happens).
Comments?
-T.