there was small production run of M1 Carbine barrels down in states and number of those are srill on the market. But. Can't get them across the border. I myself still munching an idea of machining one for myself. M1 carbine barrrrel isn't a straight pipe, there is some milling involved. Your options are to order custom barrel from trusted smith ( $$$ and months of waiting) or sleeve existing barrel with longer insert, original rstricted barrel only needs half inch or so . Don't even think you can get export permit for any M1 Carbine part., for some reason M1 carbine is banned from export down in states.