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Discussion Starter #1
I recently picked up my first Hk91 and today was my second outing to the range. First time out, 100 flawless rds no issues. Today I went out and put another 100 rds through it. Again, no issues but did notice this.



I didn't notice this wear the first outing and noticed it today after about 40 rds. Is it normal for the brass to be deflecting so far back from the ejection port? If so, will adding a port buffer help? I'm not really concerned with finish, so much, I just was curious. Ammo used is German surplus 147 gr. MEN.

Thanks guys.
 

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That is not common. Most of the ejection marks that I have seen on mine are just below the ejection port on the rails. Also, I have noticed tiny marks on the wide forearm just in front of the ejection port. Have you checked the tension on the extractor spring and function of the ejector in the trigger pack?

Best,

TC
 

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This is one of mine and you can see the common markings from brass ejection:



It is most noticeable and still very minimal on the bottom rail just below the ejection port.

Best,

TC
 

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Discussion Starter #4
That is not common. Most of the ejection marks that I have seen on mine are just below the ejection port on the rails. Also, I have noticed tiny marks on the wide forearm just in front of the ejection port. Have you checked the tension on the extractor spring and function of the ejector in the trigger pack?





Best,

TC
No, I haven't checked anything yet. I thought I'd check in with you fine folks before checking things out. Hk rifles is not my forte by any means. This is my first so I'll probably take this into my smith unless this is something I can do.
 

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Check the extractor spring when you take the bolt out for cleaning, any movement of the extractor by very firm finger pressure, and time for new extractor spring. Never go out with out one.
 

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It is hard to tell for sure in your picture, but the finish looks like it is down to bare metal. If you look at the picture that I've posted, you can see the phosphate finish showing just under the paint where it is missing. Was your rifle refinished at some point. In your picture, it looks like the rifle has a black finish compared to the trigger which is definitely blue/gray. Also, the area on your rifle has an oval shaped hue around the damage; I'm not sure if you just tried to highlight the area with some oil.

You might try forwarding your pictures to ghilliebear2000 to see if he can help you trouble shoot the problem if one exists.

Best,

TC
 

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Discussion Starter #7
Yes, I recently acquired this rifle from a fellow hkpro member and he had it refinished by Dakota Tactical...so yes, it's down to bare metal now. The oval shaped hue is just the flash on my camera, otherwise, the wear is centrally localized in that area alone.

Thanks for the help guys, I'll check the extractor spring and see if that needs replacing.

If it helps diagnosing the issue, the extracted brass was consistently damaged at the mouth plug. My buddy kept some of the brass for me to snap pics but I forgot to get it from him before I left. I can post pics when I get it back from him if that helps.
 

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What buffer do you have in there? I originally had a standard buffer and then switched to a heavy buffer and within 20 rounds had markings like those in the same location. Pretty sure mine are close to the bare metal as well.
 

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Discussion Starter #10
Standard buffer, bolt gap is .012

This is some dirty brass! Ammo way too hot? Notice the dent at the mouth plug.

 

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Discussion Starter #12
A new locking piece and +4 rollers were installed before I purchased the rifle to bring it back to spec.
 

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A new locking piece and +4 rollers were installed before I purchased the rifle to bring it back to spec.
Sounds like this rifle has seen some use, in the future might wish to think about a +6 roller (would have to be US made most likely http://www.robertrtg.com/g3rollerext.html).
While checking your rifle during the next cleaning, take a look at the locking piece and see what it is marked, take a close look at the "roller window" in the bolt for deformation and try cleaning the inside lip on the extractor (may have to use a probe carefully if a lot of built up hard residue). Out of general interest did this rifle come with a full auto bolt carrier?
 

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The dent is your HK91 simply making it's mark because you do not have a port buffer. I consider a port buffer essential if for nothing else so that I am less likely to get smacked by a team mate or at the range by someone who took a hot brass in the head or down his girlfriend's blouse, but it is also kinder to Boxer brass so I can more easily reload it

EDIT: HK brass will be dirty because of the chamber flutes.. they allow gasses to blow past the brass a bit. It's the price you pay for better reliability
 

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^^^I dunno about the port buffer being the issue. I've got several 9X series rifles and none have markings from brass in the area directly behind the port and none have buffers. I also disagree about the brass ejection too, unless you're standing at the 2 o'clock in front of an active shooter, you should not be getting hit with the brass unless there is an issue with the rifle. I have however seen brass eject to 3 o'clock before off a rifle.

Agreed about the way the brass looks.
 

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I have however seen brass eject to 3 o'clock before off a rifle.
Yep... the ejector is going to need to be replaced soon when you start hitting the 3 o'clock pattern. HKs beat brass up, no getting around that. You want pristine brass, go get a bolt or lever action...
 

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Discussion Starter #18
Yep, my brass is ejecting at more like 3:15! I'm going to get into it tonight and check it out. I'm sure I'll have more questions. As for the bolt carrier, I'm not sure if its FA or SA, what's the easiest way to tell the difference? I'll also look at the locking piece to see if there's anything marked on it.

Thanks for the help gentleman...more questions to come I'm sure.
 

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^^^I dunno about the port buffer being the issue. I've got several 9X series rifles and none have markings from brass in the area directly behind the port and none have buffers. I also disagree about the brass ejection too, unless you're standing at the 2 o'clock in front of an active shooter, you should not be getting hit with the brass unless there is an issue with the rifle. I have however seen brass eject to 3 o'clock before off a rifle.

Agreed about the way the brass looks.
Even if that is always true what about squad training or actual action? I sure would not want a stream of hot 7.62 brass into my bare anatomy. Just sayin

My HK91 and my PTR 91 do eject at about 2 O'clock because they are low mileage and in good condition/conformation but they can deflect off at a tangent at a range barrier too
 

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It's not the extractor, the brass is definately coming out fine. It's not the stock buffer, the brass is already out the port before the carrier hits the buffer. If there isn't a problem with the ejector there soon will be. I believe there's a problem with the gun opening with to much velocity and/or the ejector is damaged. Check bolt gap, inspect the ejector to see if the face is peened over or bent. My .02.
 
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