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  1. #31
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    So an update... Learned some stuff in the process, but in the end, I'm not really sure I've "solved" anything. And I'm not certain there's anything to solve.

    A recap...the players:

    "Problem Rifle": Makes marks on spent, ejected brass. Does NOT make marks on unfired brass.

    "Rifle C": Known good rifle, used for testing. Shoots everything fine with no issues.

    Update:

    - The Problem Rifle was checked for headspace with 5.56 gauges. Bolt closed on Go-gage...PASS. Bolt would not close on No-Go gauge...PASS.
    - Problem Rifle BCG was put in Rifle C and worked 4.0, no brass marking (this had me puzzled after it passed the headspace test).
    - Rifle C BCG put in Problem rifle and worked 4.0, no brass marking.

    Conclusion: I have no idea. At this point I can't find anything wrong with the Problem Rifle. I can swap out the extractor, but it didn't make marks when put in another rifle. Unless someone has other ideas, I'm at the point where I'll just keep an eye on it but keep shooting.

  2. #32
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    I would say you solved 98% of the problem when you took the over pressured ammo out of the equation. When fired, the brass expands to seal the chamber and with the ammo being OP it delayed the extraction window by just enough that the extractor had to have a death grip on the case to get it out. I’m actually surprised it did but that would explain the death grip marks on the spent casings. Just because the primers didn’t blow out on all off them, doesn’t mean that the rest of the cases from that lot were not over pressured as well. Hence the death grip marks on the other cases. With that said you may have knocked down that sharp edge on the extractor which may explain why you’re still getting some marks. A sharp or new extractor claw will fit nicely around the case and in most instances you won’t even know it was there after ejection. I would take that extractor out and throw it as far as you can and put in a new one. Also, with it having such a death grip on it you may have too much spring pressure. Put in a new extractor spring and O ring as well then test fire it. If you still get marks take the O ring out and fire a mag with just the new spring. If you’re not happy with the results it sounds like switching complete BCG’s from the PR with rifle “C” was a fix as well but I would still toss that extractor. Sometimes these problems seem like a PIA but this is the stuff that keeps us frosty and most of all “learning has occurred”
    The best way to survive a violent encounter is to be the one inflicting the most violence.

  3. #33
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    Huh

    Sounds like that ammo is just on the hot side..I have some reloads in 77 gr that are deadly accurate but swipes and flattened primers are the norm from it

    Also was gonna say, maybe try a different extractor and it spring/insert. I keep a few bcm kits on hand and never had a problem with them

    But I’d just shoot it some more and just keep an eye on it

  4. #34
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    A new extractor it is. I had one Colt spare, but grabbed a second, so I can still have a spare after swapping this out.

    Interestingly, regardless of ammo, it was making the marks both with and without the o-ring. It actually wasn't running an o-ring originally (didn't realize the bolt didn't have one), so way back when I was testing this stuff, I put one in. No change on the marks.

    Sounds like that ammo is just on the hot side..
    But the thing to keep in mind is that it makes the marks with ALL ammo. That's what really had me scratching my head. But like you said, I'll shoot it and keep an eye on it.

  5. #35
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    Closing this out, as I've ceased caring after the last test...

    Tried a brand new extractor with new gold Colt extractor spring. Still marking the brass. It looks like the ejector may be marking one side and the extractor marking the other. Otherwise it continues to function fine. I'll just keep shooting it.

    I also tested the popped primer ammo in two other rifles and no issues. Perhaps what Alamo mentioned about chamber tightness makes this gun not like that ammo. Whatevs, it shoots everything else fine, so I'm moving on.

  6. #36
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    Like you said, if all the function is there, drive on...
    The best way to survive a violent encounter is to be the one inflicting the most violence.

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