Hi Frank,
After some really consistant luger shooting the last couple of years, here are the parts I wasted:
1937 S/42
-Ejector spring. Was a repro, replaced by original one. Works better
VoPo WW1/S/42 combo
-Firing pin retainer. Probably due to previous owner shooting home-made crap ammo.
1913 Dutch
-Grip safety leaf spring. Well, after 90 years...
1972 Mauser Parabellum
-Bought with slightly blown-up barrel, again previous owner cooking his own ammo...
I shoot about 100 rounds of S&B 124 grain every week. Both the S/42 and the VoPo have been rebarreled with East-German barrels in the past, so nothing really valuable to break.
I'm easing off on Dutch M11 as it's in too nice a condition to break something expensive. Also replaced the original (fragile) grips on the Dutch and shoot with VoPo bullseye grips that were modified to fit a grip-safety luger.
Also made sure that all firing-pins are of the 'vented' type.