I'm pretty sure the L39A1 is in fact a No4Mk2 converted with a kit of parts. The receiver markings still have the No4 Mk2 engraving and serial number. A real L39 would have it's donor rifles number milled off and the new I.D. marked on it.
Agreed, it's made up. When you consider that there are only three hundred odd Enforcer's surviving, it's criminal to deactivate one.
The only exception to this (from my perspective) would be if the action body was unserviceable for some reason..