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Posted: 3/22/2012 2:58:21 PM EDT
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Running a MP15T and originally it chewed up everything with the stock mags or magpul mags. Wolf, Win white box, Eagle black box etc. It might have 1500 rounds through it total.
Lately it seems like it's not cycling far enough to pick up the next round, every 5-10th round, same ammo and mags as before and is consistent across them. I've gone through and did a full strip/clean on it twice now with no improvement. Even went back and checked a couple cleaning guide posts to make sure i wasn't missing anything. I even took an old buffer/spring and shaved the buffer down and cut the spring down just to try and "force" it to cycle in case it was a gas issue, no luck. The only things that have changed from stock are it has an ACE stock, and a Geissele trigger, ergo grip, and a eotech. I'm going to put the factory stock/recoil tube back on, and go back to the factory trigger, but the gun was cycling fine with the ACE stock before, perhaps the ACE tube was bent/damaged and is binding things up, but the bolt seems to be smooth when ran with the charging handle. Once and awhile it will partially pick up a round and jam with it high against the chamber, on those rounds it looks like the bolt didn't go far enough back to pick up the round cleanly, you can see where it started gouging the round just after the case rim and then further up the case. I've also noticed a couple times on the last round it won't hold the bolt open. It just baffles me because the first 500-1000 rounds it chewed everything up with no problem. Thanks in advance Todd |
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Quoted:
Looks like I found it, I pulled the forearm to look for any gas leak signs, the two gas block set screws were both loose. Can they be lock tighted, or staked to avoid this again? Yes, use Red loctite on the gas block set screws. IF later you need to remove the gas block, throw a old allen wrench in the allen screws, the heat up the wrench it a torch to transfer heat tot he screws/loctite to break down the bond so you can back the screws out without stripping the sockets. |
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No joy on the FTF, problem still there. I really thought the loose gas block was the problem. I think it was actually worse if that's possible, would only fire one round at a time and wouldn't hold a bolt open.
Checked the gas key block, staked and tight. Entrance to the gas key block does not look damaged or worn. Bolt passes the stand up test easily, but I changed the gas rings anyway. Changed back to 100% factory parts aside the trigger, still running a cut down recoil spring and stock carbine buffer. marked and double checked that when I put the gas block back on that the gas block hole was lined up with the barrel hole both in circumference and distance to the barrel shoulder, verified again when I removed it. The only thing I see this time is that the "mushroom" end of the gas tube has a small spot (maybe 1/8") that's worn flush with the tube, it also appears there might be some carbon build up where the front of the gas tube enters the gas block, not a lot just around the tube rim. Ordered a new gas tube, gas key block, and gas block (the gas block IMO was pretty loose on the barrel, it would turn easily and slide on and off easily, not "sloppy" but not snug either). I'm not convinced from reading other posts etc. that the wear on the gas tube I'm seeing is enough to cause this much issue though. The MP15 seems to be over-gassed as it is and I ran across a lot of posts where the whole "mushroom" could be worn down flush and it just barely caused problems, but it's a cheap experiment, and perhaps the tube/gas block/gas key block was more damaged than I think when it was being fired while the gas block was loose. Though it wasn't fall off/move around loose, just not tight either. After this I'm out of ideas/options, it will have to go back to S&W. Something significant must be wrong because for the first 1000 rounds this thing ran like a top with any ammo. |
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