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Discussion Starter · #1 ·
I was trying to sight in an hk 91 I aquired in trade and during the course of using 308 federal match I noticed a quite variable problem. I had numerous blown primers, failures to extract, and some very violent recoil. Now I have several 91s and none of them have acted this way. I suspect my extractor is the problem, but I dont know could you guys give me some pointers?
 

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I would guess you have a bolt gap problem. There is a sticky in the long gun forum that describes how to check you gap.
 

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I had a bolt gap problem like that that seperated a collapsible stock. The recoil was so violent it felt like shooting slugs or worse. I replaced the rollers and back on track. The stock had to be reworked. I shot nothing but Fed GM Match through mine, I never had the blown primers. The impulse was so violent my extractor cruched the brass. I have noticed the guys that shoot battle packed ammo with the same problem have the same issues but with reduced recoil. It must be load differences. Good luck.
 

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is it a real Hk91

or a clone US made gun
 

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Sounds exactly like what happened with my POF 416 14.5 upper. Same problem with the brass and bolt/carrier. I tried two different kinds of ammo, two different mags, a heavy extractor spring and guess what - STILL HAD THE PROBLEM!....

I have since realized that my POF upper has a headspace issue. I purchased a Go and No-go headspace gauge for my upper and the No-go gauge slammed the bolt completely closed. After that my No-go gauge was stuck in the barrel. I was so fed up at that point, I shipped everything back to POF and told them to figure out the headspace problem. (Ok enough of me ranting).

Use some mechanics gauges to test your bolt/gap on your 91. If you need to add additional rollers - it will correct the problem immediately. Just make sure you are in parameters outlined in the sticky!

Good luck!
Conrad
 

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Discussion Starter · #7 ·
It is a real hk91. I am in the process of purchasing an entire new bolt from another board member and will then have to purchase some rollers and then figure out how to repair the old ones. I guess it will never hurt to have spare parts now. I really appreciate all the help from the board members. I feel like you guys nailed my problem.
 

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Before you spend all the cash on a new bolt. Check your bolt/gap. You may only need to get some +/- rollers for your bolt. You can get some gauges from you local auto zone.

Why spend the money if you dont have to....

thanks
C
 

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It is a real hk91. I am in the process of purchasing an entire new bolt from another board member and will then have to purchase some rollers and then figure out how to repair the old ones. I guess it will never hurt to have spare parts now. I really appreciate all the help from the board members. I feel like you guys nailed my problem.
Depending on what and where the tiny bit of change has occurred, changing the bolt may not help the issue and in some cases, depending on how the tolerance stack up, could make it worst.

Bottom line is when ever you swap bolts and/or change bolt parts (including the locking piece) - really need to check bolt gap.

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Changing rollers is not hard (in particular when you let friends do it - Chuck and Jim ;-).

I recommend getting along with the new oversize rollers, a new roller retaining plate and two roll retaining plate pins (they tend to jump and hide on the bench at 2AM ;-). While there a assorted guides on line, the short version is take your bolt assembly out of the gun (all safety rules apply with being unloaded), remove the bolt head, remove the locking piece if it has not fallen out, look inside the bolt head to see how everything goes together, punch out the roll pin, remove the retaining plate and rollers. Place the old parts in a bag, and then open new parts .... reverse everything and once back together check the head space (if not enough change, then repeat with the next size up roller).

Thus if you have several HKs, getting an a couple sizes of rollers is not a bad idea (along with a few extra extractor springs ... you have basic HK parts kit ;-).
 

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Discussion Starter · #10 ·
Man you guys are great. All very good advice. I wonder where a person can get the rollers and other parts?
 

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Five Options:

1: I tend to go to KCR and pick up the parts from one of the five plus HK suppliers ... rest of the guys I shoot with tend to just take the parts out of my black bag ;-).

2: Check the "Classified" section here

3: Check with one of the following two guys:
Adam at: http://www.hkparts.net
or
Gordon at: http://www.hkspecialist.net/

4: Google your part and/or place a want to buy add (not worth the effort IMO for little items vs. buying from Adam or Gordon).

5: Check with your department armor or HK Smith .... but they usually just fix what is broke themself ;-)
 
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