Hi Joe,
The Non-Firing display only MGC68 MP40s were heavily modified to stop them firing even Cap loaded cartridges.
I've seen lots of examples having holes drilled through the Barrel Nut, right through the Trunnion and Chamber.
Also seen receivers drilled straight through into Trunnion and Chamber.
Other mods' were done, ground Boltfaces, split receivers, split Trunnions / Chambers, Blocked barrels, plugs fitted inplace of the Det. Pin.
I've not seen one with a drilled hole in the barrel that far in front of the barrel nut though.
These can be converted back to Cap Firing with work and replacement parts but it gets rather expensive now as parts become more and more scarce
Parts are available though, folks converting MGC68s to Blank Firers will discard Bolts, Barrels, Trunnions, Recoil Springs and tubes so it's worth asking.
Kickback here converts them, MGCUK also so they're a good source for parts. Franky and Shazhib could help too. Ken Harris in the 'States has a barrel and other parts... look in Gunbroker.com, his username there is Model Gun Collector USA
Value depends on so many things. Better to find out exactly what condition it's in and whether or not it's a Display only or a cap firer
_________________
Cerwyn
Hobby collector of Replica model guns and Militaria.
also member of Living History Reenactment Groups.