5.7 Johnson and M1 Carbine

[floydthecat]

Sounds like an excellent decision to me. I wouldn't touch that project with a stick. I've never had the desire to do something "just because." And sticking a cartridge in an M1 carbine receiver with almost twice the case capacity "just because" seems a poor challenge to take up.

If one has some old parts lying around, a “just because” fun conversion is 7.62 x 25. You won’t gain any performance or accuracy from it, but you can form your own brass easily enough and shoot Spitzer profile projectiles, or standard .308 carbine projectiles.