doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com High Energy Black Powder Loads?

Let's say you have a 12 gauge gun and want to shoot a heavy charge with a 600 grain hard cast slug. (Assume recoil isn't an issue, although I imagine recoil will be stout). 150 grains would roughly equal 2500 ft lbs. Would 200 grains equal 300 ft pounds? Does anyone know what the approximate pressure would be?

It seems like 150 grains in a 72 caliber with an equivalent weight bullet would manage more energy than a 150 grain charge in a .45 or .50 caliber rifle. Is this due to the different burning dynamics of black powder? (Does the wider cross sectional area allow more of the powder to burn?)

Velocity is obtained by applying force to the base of the projectile. The velocity is of course proportionate to the amount of force as well as the area of the base.
The areas of bullet bases are relative to the square of their diameters. (.72/.45)� = 2.56. Thus if you had an exactly identical pressure curve a 235 grain bullet would be pushed to the same velocity in a .45 as a 600 grain one in the .72.
A 500 grain bullet (old government weight for the .45-70) would have to reach 1500 fps to develope 2500 ft/lbs, a 600 one 1370 fps. It would take a good bit more pressure to get that 500 grain bullet to 1500 fps from a .45 caliber barrel than to get the 600 one to 1370 in a .72 bore.