The blued magazine's a late replacement.
As to numbering - originals were numbered to the individual weapon, but period replacements usually give evidence of an acceptance mark, though they're usually free of numbering.
Thanks to the Russians opening up their WWII captured weapons armories a few years ago - there are still many original magazines extant - finding one should be fairly easy, though prices are rising exponentially.
You don't need a gunsmith - you need to find one of the big NRA Guides on Handgun Disassembly, and follow the instructions - remembering that with automatics, it's 'assemble in reverse order'...
Scouts Out!