Extractor Pin

How do i make my PWA Commando Ar-15 Reliable?

I have had several problems with the rifle. first it would not extract about every third shell. I installed an extractor D- Fender d ring. Problem solved. Now I am having trouble picking up the rounds. I have polished the chamber, installed new followers in the mags and the mags are properly seated. It is also not firing every round. The firing pin is not striking hard enough, I think. The Aft carrier key screw sheared off. How did that happen? And Last there are (chatter Marks) on the underside of the bolt carrier on the ramp near the firing pin.

1. Would not extract? Insufficient extractor tension. D-Fender solved.
Or: Restricted movement of bolt carrier. Could your carrier key screws be loose?
If they sheared, yes. Stake the next set.

2. Won’t feed? Restricted buffer assembly. This also causes first problem. Bingo!
Take out buffer and spring. Clean.

3. Won’t fire? Improper assembly of firing pin. Assemble correctly.
Or: Too much oil in firing pin recess. Clean with pipe cleaner.
Or: Too much carbon on firing pin, or in firing pin recess. Clean.

4. Chatter marks? -???

MP5 w/worn out extractor Spring..German Push-pin MP5