max 11/15 jamming

10mmlover

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If you want to watch an exercise in frustration, look at the above video. So far the nib m11/9 has been flawless (other than the time I tried 9mm hollowpoints). I've got a bunch of Lage and PS uppers that have all been 100% with all sorts of magazines. I recently got the max 11/15 (after a long backorder since they were working on the one for the mac 10) and put about 200 rounds through it. All 200 rounds of pmc x-tac with magpul 30 rounders and a couple of D60 drums fed without a single hiccup. Today I brought it out for the second time and right from the start it had an issue with both drums and all magpul 30 rounders where the bolt flies forward, but it pushes the round forward maybe half a centimeter and stops. If I cock the bolt back again (it's only a little forward) and fire, it'll always push that round the rest of the way and fire it. How many rounds it gets through before the same kind of stoppage seems random. Usually it's a few rounds, but every now and then it's 20+ rounds. Maybe all the lube burned off on the first session and I just need to slather it in TW-25? The gas seems tuned correctly as the jams are right off a fully cocked bolt, not just while firing.
 

A&S Conversions

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So l am clear, you have not cleaned the upper, the problem is loading the first round into the chamber of a fully loaded mag, is that correct? If so I would clean the upper and down load the mags by one or two rounds. You are still breaking in the upper at 200 rounds. My experience with PMC X-TAC has been that it is somewhat of a dirty ammo. It gums up my uppers a little more than most. So a dirty upper will tend to have more resistance than a clean one. More resistance to function will require more energy to function.

If the issue persists on any rounds after the first in a fully loaded mag, then I would increase the amount of gas through the gas block. Like the rest of the upper, the gas block will have residue inside it. That residue will tend to restrict gas flow. Lage does make a stronger recoil spring. The increased spring pressure would require more gas for function, which will increase your ROF.

Scott

ETA After watching the video, you definitely need to increase the gas. The bolt is going back far enough to catch the sear, but the grime inside causes resistance. Give it a little more gas and it should run.
 

ScubaLoser

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Hey OP, I think I’ve seen all your M11/9 YT videos. Looking at this latest 11/15 video, your 11/15 ejection looks real weak. The spent casing is barely being ejected where it should be flying a good few feet at your 3-4 o’clock direction. To clarify this is from a bird’s eye view, so 12 o’clock is the barrel muzzle down range and 3 o’clock is to your right 90 degrees. I would first ensure the AGB is properly installed and not moving, then adjust your AGB to allow more gas. Report back if you’re still having problems.
 

mtlcafan79

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TW-25 is white grease right? I would clean that all off and use an oil instead. The only issues I have with mine is that it won't feed from a beta mag. Everything else runs like a top.
 

skoda

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10mm, it looks like this happens every time AFTER you let off the trigger and then press the trigger. Could there be something going on in your trigger/sear system? Do you still have the disconnector in? Just thinking out loud since I don't have one of those uppers.
 

brenbuilds

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Clean the chamber and see if it continues. I would also open the gas valve.

Be careful with grease as it can actually slow down the gun if too much is used. Grease accumulates carbon, powder and other debris and creates a sludge that can reduce bolt velocity and make a mess.

Have you tried other brands of ammo other than PMC?
 

Loco

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Use 0w20 oil, or gun oil. Please don't use grease.
 

10mmlover

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Thanks for all the suggestions guys, after reading them and looking at the video again, I think I need to up the gas. It was fine the other day but perhaps it was right on the edge of being enough. I did the procedure listed in the manual, going to the point of failure, then adding 2 clicks more gas, but perhaps it needs a little more now that there's a bit of fouling in there. My perception was that it wasn't working after being charged, but as one pointed out, it was firing on the manual charge, but not after the let off and firing again. So I think the bolt is catching on something to hold it back, but clearly it's not the correct notch on the bolt on the sear, so it's not getting the full spring force forward on the next trigger pull.
 

Slowmo

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So I think the bolt is catching on something to hold it back, but clearly it's not the correct notch on the bolt on the sear, so it's not getting the full spring force forward on the next trigger pull.
Sorts sort of what I was thinking, similar to how an undergassed AR15 can occasionally lock back part way be catching the bolt carrier rather than the bolt.
 

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