I have to agree with wlscott on this one. I too trust my life and have proven that "black rifles" will be there when you need them, if you take care of them. Now, G3, here is my problem with your equation. I have quite a bit of experience with Kalishnikovs, and I think that you are heading in the wrong direction. It's not that they can't handle the round, but by the time you mill the receiver/develop a magazines and mill the receiver and action, you could have bought a .50 Beowulf upper foar an M4 lower. The .50 Beowulf is a great little round (I bought an upper, and I love it) and it has comparable ballistics to a 45/70 or .444 (around in that area) and they have ready to buy magazines and such. I just thought I would let you know, because I too am chasing a dream of building my own guns. Some of this stuff is cheap, but finding someone with the knowledge and tools (chamber reamers, button rifling, etc) is kinda high dollar.
SAWgunner