Originally Posted by
Larry Gibson
DougGuy
"Basically, anything that offers resistance, increases pressure. Cylinder throats being undersized is one of the main contributors of resistance, and *IF* there is more resistance offered by a hard cast alloy as compared to the exact same boolit cast in a soft alloy, then in this scenario, boolit material has a direct effect on pressure."
That is an assumption I would have, and did, believe until I started actually pressure testing. With cast bullets in the 44 Magnum I haver tested the same bullet sized .429, .430. .432. and .434. In the 45 Colt the same cast bullet at .451, .452 and .454 was tested. Also in 357 magnum the same bullet was tested sized .356, .357, .358 and .360. In the 308W and the 30-06 I have tested the same cast bullet sized at .308, .309, .311, .312 and .314. All were the same alloy, same lube, same GCs (where used) and the same load. In all of those tests only the psi of largest sized bullet fell slightly above slightly above the test to test variation ES of the test. Then, even that slight raise was measurably inconsequential. The bullets were sized down within one bearing length of travel when the psi was still rising. Given it doesn't really require that much pressure to size the cast bullet what variation apparently falls within the shot to shot psi variation. Interestingly the chronographed velocities also did not increase beyond what would be normal test to test fps variation.