Armorer's Capability?

[DonVoigt]

Yes; though not all replacement parts require any fitting.
Those that do often need only a little file or stone work

Any repairs "they" could not do would be passed up the chain for repair.

In my experience, even though parts were fitted and numbered; it is possible today to select parts that will assemble without any need to "fit" into a completely mismatched shooting luger.
Only "problem"is having enough parts to choose from.