Early carbines were not cut for M2 parts. Most M1s will take the parts, but this does not make them M2s.
I said "if" the gun does not have the FA parts!
The other scenario is that the M1 gun was legally converted, and you bought it without the FA parts-it would still be a machinegun. Once a gun is registered as an MG-always an MG.
UNLESS.....the fire control parts are registered as an MG. Confusing, isn't it?