A little background. I make muzzleloaders that shoot smokeless powder. Most use Savage actions and premium barrels. I want to test some experimental breechplugs and don't want to scrap an expensive barrel so I am looking for a cheap substitute. I can pick up a NEF Handi-Rifle in 45-70 or 50 S&W for about 200 dollars complete....can't get much cheaper than that /ubbthreads/images/graemlins/smile.gif I really want a cheap 45 to play with since this is only to experiment with, and accuracy is secondary. The Handi Rifle comes in 500 S&W ( 50,000 psi )and 45-70 too, but the 45-70 is generally a low pressure cartridge since its origins are in BP. Two considerations need to be taken into account as to load pressures: 1) The Barrel. If the 500 S&W Magnum is a 50,000 psi cartridge, AND the 45-70 and the 500 S&W utilise the same barrel contour then I think that the barrel is up to the task in the 45 version too; 2) The Action. Bolt and Falling Block actions are known for their strength. Break open actions and lever guns are not. Clearly the action needs to be able to take the full pressure should you experience a case head separation. The 500 S&W Case is 0.526 in diameter under the head which would translate to a case separation pressure of 10,865 and the 45-70 Government is only .505, which translates to just 10,000 assuming a 50,000 psi load. My question is does anyone have any knowledge about the Handi rifle that would make you not use full power loads in a 45 barrel ( 50,000 psi)? I would prefer an open discussion, but if someone would prefer to PM or email me their thoughts, they would be very welcome too edge.