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Discussion Starter #1
HK91 issue...

I am using a Silencerco 762 with QD brake. I am also using a Enhanced Heavy Buffer from HKParts listed below.

https://www.hkparts.net/shop/pc/Enhanced-Heavy-Buffer-G3-91-PTR-114p16482.htm

The rifle operates fine. The problem is the increased blow back pressure is sending the bolt carrier back at such a rate it is crushing the metal housing on my stock. It has bent it to where there is a gap between the receiver and the stock as shown below.



Any suggestions?

Alan
 

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Wow, first I've heard of this. A couple of things that popped to mind are checking the bolt gap and possibly using a different locking piece, something that will delay the opening of the bolt a bit more.
 

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Change the locking piece so that the breech opens later and doesn't hammer the rear? Like an MP5SD.
 

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interesting, please change locking piece and bolt gap. did you install the heavy buffer?! I’ve run my 91 often with a suppressor and never had a problem, though i also never used a heavy buffer.
 

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I've heard of this before. I plan on trying to suppress my G3k clone (SBR'd) and need to figure out if there's a suitable locking block for the short barreled .308's.
 

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Discussion Starter #10 (Edited)

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Discussion Starter #12
"Do check your rails for bulge damage and your bolt gap. Your signs are of really excessive recoil energy."

1. When you say "rails" you mean the receiver the BCG slides down upon recoil?
2. Bolt gap...how do I check that? Measuring tool? I'm ignorant here.

Alan
 

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"Do check your rails for bulge damage and your bolt gap. Your signs are of really excessive recoil energy."

1. When you say "rails" you mean the receiver the BCG slides down upon recoil?
2. Bolt gap...how do I check that? Measuring tool? I'm ignorant here.

Alan
Not to be a Richard here but you spent the money to buy the rifle AND a suppressor for it and never bothered to learn the single most important check it requires? Here is a link to a video on how to measure it. The part about cleaning he kind of glosses over is IMPORTANT to getting an accurate measurement. The measurement is done with a simple set of feeler gauges available at any hardware or auto parts store.

https://www.youtube.com/watch?v=ipeC1Yq2F4M
 

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Not to be a Richard here but you spent the money to buy the rifle AND a suppressor for it and never bothered to learn the single most important check it requires? Here is a link to a video on how to measure it. The part about cleaning he kind of glosses over is IMPORTANT to getting an accurate measurement. The measurement is done with a simple set of feeler gauges available at any hardware or auto parts store.

https://www.youtube.com/watch?v=ipeC1Yq2F4M
We all had to learn somewhere. Outside of HK roller-locks, I never heard of such a thing. Headspace gauges aka Go/No-Go gauges, sure. But not checking headspace like that. Once you learn it, it becomes second nature.
 

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OP you need my G17 LP which is correct for a G3/91 carrier.
The tail on a 17 is not correct in size although it can be used but not recommended.
Do not waste money on cobbled up (take 2 old G3 buffers) and weld together.
Get a heavy buffer (no such thing as a 2 stage).
MM
 

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Any damage to the receiver? that looks like it would have stretched the receiver or caused bulging .
 

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Discussion Starter #18 (Edited)
I bought the suppressor for a few platforms. I just took it out and shot maybe 50 rounds on the 91. I will look into it. I don't think it caused any damage.

Thanks for the responses.

Alan


"The measurement is done with a simple set of feeler gauges available at any hardware or auto parts store."

I'm going to get me one. Understand this rifle has performed flawlessly since I bought it years ago. All of these new issues are suppressor related.
 

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Discussion Starter #19
OK there appears to be very slight "roller marks" on the rails. The pictured mark is the worse of the two the other side is less so.



I know you can barely see the light difference there...
 

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We all had to learn somewhere. Outside of HK roller-locks, I never heard of such a thing. Headspace gauges aka Go/No-Go gauges, sure. But not checking headspace like that. Once you learn it, it becomes second nature.
Possibly but it seems to be one of the most prolific things that comes up during a search for information and isn't it mentioned in the manual as well? I know the Owner's Manual from PTR has a whole section on it.

New rifle, that has an entirely different operating system then what a person is used to dealing with and then to not do even some cursory research is kind of negligent in my mind.
 
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