List of most common broken parts I've seen in 18 years Luger competitions:
1 holdopen at least 4 or 5 that I can remember (best solution remove before shooting).
2 ejector - again at least 4 - No biggie not a numbered part, just keep fitted replacements handy or better have a backup pistol (competition only advice), for the casual shooter, just swallow your tears and your pride go back home and buy a replacement, just don't forget to have it fitted to your pistol.
3 rear toggle opening cracks near the knobs, seen it twice. Always a heartbreaking bummer. Only solution replace, preferably by a competent gunsmith who knows Lugers and preferably of the same vintage
and maker of the rest of the toggle train.
4 Extractor breakage - same as the above.
5 breech block breakage (happened to me and it was a matching part
). Cost me money and my defending Champion title that year.
Another very good reason for a backup shooter.
Never seen a firing pin breaking. But, if yours is not fluted. Get one. My breechblock most likely failed because someone had swapped the original fluted firing pin of my BYF 41 for an older unfluted one, and I had a batch of bad ammo with excessive headspace (totally my fault cause I made them) and had pierced primers.