I never thought about the M1 Carbine, but if you want to use it for self defense it might be a good idea to find some of the Cor Bon loadings meant for the 30 carbine. I think theyre called Pow’r Ball...but I could be wrong.
Yea, but they're pretty expensive, and you are contemplating longer engagements with a long gun, so you need more than you would for a handgun. I have 1,000 rounds of soft point ammo for mine however. Better than ball, but not much more expensive.