[Mac Cat]

The hold-open is the only part you don't need.

Some of the aftermarket replacement parts are well made, but some are not.
Particularly springs and firing pins.
Be careful. If they look too new or have the wrong color, be suspicious.

Try to buy original German DWM or Mauser parts if you can.
Parts from a known luger are best.

Most of the military small parts were marked, but only a few of the commercial parts were.