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Discussion Starter · #1 ·
I got my form 1 approved for my Z5P back in late October and have been trying to fix this issue ever since. The way I wanted to have my SBR set up required that I replace the bolt head as a 922r part. When I replaced my bolt head my reliability went from 100% down to about 15%, and this was with me swapping my MKE parts into a stripped RCM bolt head. The bolt gap stayed constant after the swap at .25mm.

I thought that maybe the swap weakened the extractor spring, so I replaced that to no effect. I also replaced the extractor itself with a RCM one just in case there was some compatibility issue, but that didn't make it any better either. I then bought a 110 degree locking piece because I've read that has helped some in the past, but that didn't work either. Then last week I bought new rollers to bring my bolt gap up to the ideal .45mm in doing the last thing that I could conceive of to fix the problem, but it didn't change a thing. I even tried using a rifle extractor spring but that only bought me an extra one round between failures before it started up the old FTE pattern. Today I brought my old bolt head and locking piece to the range just to make sure that nothing changed with the gun itself, but it went purring along perfectly for every round I put through it. So clearly the gun is capable of working reliably, but the trick is getting it to do so while being 922r compliant.

Has anyone else run into issues like this? The FTEs that I get are so bad that I often have to disassemble the gun completely to clear them, and they happen every 2-3 rounds. I would honestly be less confused if I was getting similar issues with my stock MKE bolt head.





 

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848 Posts
How well does the RCM combo hold the case. Loose or tight compared to the MKE setup?
 

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Yes, although my FTE's were not occurring at the high rate you've encountered. Installing a German extractor in the RCM bolt solved the problem in my ATI/MKE gun.
 

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The Librarian
MP5-N and HK23E-K
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5,703 Posts
Find other parts to be 922r compliant and put the MKE bolt head back in. Ejection problems are related to the ejector lever, e-lever spring, extractor and extractor spring related. Btw, MKE bolt head is the gen 1 style and RCM is a F style upgrade.
 

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Aren't the roller retainer plates different between those two versions of bolts? Was the MKE retainer forced into the RCM bolt?
 

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You might need the current ejector lever to interface with the F syle bolthead properly. MKE trigger packs have the old square version.
 
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