Trigger return spring
Firing pin block spring
roll pin 3 X 14mm HK suggests to replace these EVERY time you knock one out they should be replaced with a new fresh pin.
Mag springs (super common issue)
O-rings (if your firearm uses them)
There may be more but this covers the main wear and tear components. I hope this helps.
A forum dedicated to and laser-focused on Heckler & Koch firearms, Heckler & Koch accessories and the owners and enthusiasts that love them! Come join the discussion regarding HK pistols, long arms, NFA arms, HK accessories, HK history and trivia and more.