I don’t think allowing such fast access to the M5 is a great idea. It would come in at 1CP timing.
It would only be reinforcing conscripts, CEs, Soviet mortar, and zis gun for the most part, I don't think it would really be too strong. If Maxim was still there it'd be OP as fuck but that's the whole point
If you want it reinforcing penals that's 50 fuel you'd have to spend before t3, and that's without con side-techs