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Thread: Help w/ intermittent FTE/stovepipe issue

  1. #31
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    Quote Originally Posted by Barnacle Bill View Post
    I haven't had much trouble before this. I had a CMMG that didn't like PPU 75gr OTM, although it ran fine in other AR's. All this shooting of it has put a pretty big dent in my PPU M855 stash, with only one or two 200-rnd packs left now. I think I'll replace it with Federal as you suggest, since that is starting to show up online at reasonable bulk prices. I have a whole bunch of PPU M193, but I haven't seen any issue with that (in all honesty I haven't shot a lot of it yet, though). If I was going to use it for anything besides practice, I wouldn't want M855 but my understanding is that Mk 318 is more or less the same trajectory and the 9620 now has an ACOG on it with an M855 ballistic reticle.

    So, next back to the original issue in this thread, the LW carbine build and its stovepipes. I have a BCM bolt rebuild kit on hand I can install, but since it worked fine with the Mk 318 and only started acting up when I switched to the PPU M855, maybe the thing to do is just shoot a bunch of other ammo and see what happens. Interestingly, the 6520 had been zeroed at 50Y with HSM's 75gr TAP-clone load, and the irins only need one click to the right from that zero to be on with the Mk 318. I have a lot of that stuff, so maybe I'll see how it does in the LW. Or, I can drop the bolt from the 6520 into the LW and see if that fixes the stovepipes (the 6520 didn't have any problems through 100 rounds of the PPU M855).

    I assume the 6520 is your 6920, just a typo and not a third weapon.
    Still only malfunctions are with the PPU....I think you can assume it was ammo related and some lube by using the grease instead of oil. I would confirm in your LW build with other ammo though.

    You could also call PPU with the Lot numbers to see if they have had issues with that lot. Are all the Battle packs you have from the same Lot that you have been trying with errors?
    Last edited by steyrman13; 08-23-13 at 15:16.

  2. #32
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    That is a wives tale and has ZERO impact on the operation.

    Quote Originally Posted by bluejackets92fs View Post
    Just for shits and giggles. Check your rings on your BCG and make sure the slots haven't lined up.



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  3. #33
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    Quote Originally Posted by steyrman13 View Post
    I assume the 6520 is your 6920, just a typo and not a third weapon.
    No, the 6520 is indeed a third weapon, a Colt carbine model that comes from the factory with an A2-type carry handle upper receiver & 16" pencil barrel. It was brought into this matter in response to Iraqgunz' suggestion "Use an AR that hasn't been dicked with at ALL and then fire the suspect ammo. If it malfunctions then you can start to blame the ammo. I would try the lock back test first for about 10 rounds."

    The result of that test was it passed the lock back test 10 out of 10 times each with both Mk 318 & PPU M855, and digested a total of 100 rounds of each without incident. It did so from a state of being freshly cleaned & lubed with Slip 2000 EWL instead of the incumbent Tetra grease, as suggested by several including yourself.

    The 6920 got into this because of a suggestion upthread to swap bolts in the LW with one that was known to work. In attempting to confirm that it was still working after its recent trip to ADCO, I ran into the short-stroke problem.

    Quote Originally Posted by steyrman13 View Post
    Still only malfunctions are with the PPU....I think you can assume it was ammo related and some lube by using the grease instead of oil. I would confirm in your LW build with other ammo though.
    Well, the short-stroking on the 6920 actually started on the Mk 318, after having already digested without issue in the same range session 90 rounds of it plus less than 10 rounds of 1980's-vintage Norinco. It then continued short-stroking with the PPU, almost every round. That was with well-aged grease on the bolt & carrier.

    Coming back to the 6920 after cleaning & relubing with Slip 2000 EWL, then it digested 100 rounds each of Win Q3131A & Mk 318 plus 30 rounds of the PPU. At that point, it started short-stroking again for 2-3 rounds, then failed 2-3 single round in the mag lock back tests, then miraculously cleared up & started passing lock back tests and finished up the rest of the mag the problem started with without further incident.

    So, at this point I think the 6920 looks fairly GTG, although I'll probably get some Federal or PMC X-TAC M855 and see if that works OK.

    I agree that next is to try the LW build, cleaned & relubed with Slip, with some different ammo. Debating whether to install the BCM bolt rebuild kit, or at least the extractor spring & insert (and maybe o-ring) from the kit. Also to swap in the bolt from one of the other carbines if it acts up with anything besides the PPU M855.

    Quote Originally Posted by steyrman13 View Post
    You could also call PPU with the Lot numbers to see if they have had issues with that lot. Are all the Battle packs you have from the same Lot that you have been trying with errors?
    Unfortunately, I didn't save the boxes from the one I was shooting, and I shot it all up. The ones I have left are different lots from each other, so probably from the one I was shooting as well. IIRC, I bought this stuff one pack a month back around 2008, kind of slowly building my stash.

  4. #34
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    Gotcha, I guess I got lost or confused this thread with another one that popped up the same time with similar issues and lost track of the 6520 coming into play.

    It might be a combination of lube and ammo together with it sitting right on the threshold of working/malfunctioning. Do you have any weak ammo like pmc bronze or the like to try in it?

    I was bad about throwing the boxes away before too. I started tearing the lot number off one box and tossing it in the ammo can with the ammo so I would have it available.
    Last edited by steyrman13; 08-23-13 at 18:55.

  5. #35
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    Quote Originally Posted by steyrman13 View Post
    Gotcha, I guess I got lost or confused this thread with another one that popped up the same time with similar issues and lost track of the 6520 coming into play.

    It might be a combination of lube and ammo together with it sitting right on the threshold of working/malfunctioning. Do you have any weak ammo like pmc bronze or the like to try in it?

    I was bad about throwing the boxes away before too. I started tearing the lot number off one box and tossing it in the ammo can with the ammo so I would have it available.
    Everything I have in hand right now is 5.56-pressure except for some PPU 75gr OTM. The old Norinco stuff was .223-pressure, but I used up the last of it during this saga.

    I guess I need to start keeping some kinda record on the lot numbers. I keep a notebook in my range bag & record various things including weapon, load & quantity fired. Just need to add the lot from the boxes along with the load.

  6. #36
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    Happy ending to original problem

    OK, so I finally got out to the range again with the LW carbine - freshly cleaned & lubed with Slip 2000 EWL - and 10 Pmags pre-loaded from my newly arrived case of PMC X-Tac green tip.

    Flawless.

    Also the Slip seems to have not cooked off to any great degree, since everything still looks wet.

    Finally, although the X-Tac has green paint on the bullets & red primer seal, there isn't green & red confetti all over the action like with the PPU (even after 300 rounds).

    So, looks like the LW carbine is now also GTG.

    Thanks to everybody who contributed to this outcome

  7. #37
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    Good to hear. A malfunctioning carbine isn't much good for much of anything.
    ˇˇKawaii Desu Ne Haruhi-Chan!!

  8. #38
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    Quote Originally Posted by Tzintzuntzan View Post
    Good to hear. A malfunctioning carbine isn't much good for much of anything.
    Yeh, and this one was intended for home defense, plus to train my petite little wife.

    Forgot to mention above, I did install the BCM bolt upgrade kit in its entirety.

  9. #39
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    Final installment

    OK, so I got the chance to test the PMC X-Tac green tip in the 6920. 300 rounds through 10 Pmags, no problems. I did not clean it after the range session described in my 08-22-13 post, but did take the BCG out and spray it with some more of the Slip 2000 EWL, and squirt some into the holes in the side (the ones visible through the ejection port).

    So, at this point I'm concluding that the issue was mostly the PPU green tip and a little bit excessively-aged Tetra grease.

    I'll probably stick with the Slip 2000 EWL now and drop the Tetra. When I bought it, I also bought some of their EWG grease and may test that in autopistols. I bought some Slip 2000 EWL 30 as well, but I think I got a bad or old bottle (didn't buy direct from Slip 2000). Slip says "It contains a proprietary thickening agent that makes this lubricant consitency like a 30wt. motor oil. It pours almost like honey." My bottle was more like old honey after it sets up in the jar and won't flow even if you hold the jar upside down, but you can still dig it out and spread it on something. I am interested in a product that will neither migrate away from where I put it on the weapon or set up if the weapon sits in the safe a long time, so I may order a fresh bottle of the 30 direct from Slip.

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