Quote Originally Posted by 26 Inf View Post
I'm guessing you just swapped BCG's and not just the bolts.

Swap the bolts into the other BCG and see if the malfunctions still occur. Think about this and see if it makes any sense - FTE's are sometimes caused by the weapon beginning to cycle before the case has contracted after firing - over gassed. If one bolt doesn't seal as tight in the BCG (worn gas rings) then it might let the weapon function because of a slight delay/less abruptness in cycling. So my theory is the new BCG is tighter and that combination, combined with the shorter gas system on the 11.5 is causing the FTE's.

Also check the carrier keys to see if you have any signs of gas leakage - 'v' shaped carbons jets.

Hey it's one o'clock, the only reason I'm up is because my daughters completely hosed up the tub and toilet in their bathroom. Girls.
OK, I did as you suggested and swapped the troubled BCM bolt into the DD carrier and the DD bolt into the BCM carrier. With the BCM bolt in DD carrier, the first magazine was slow going, failures every 2 rounds or so. After the first 20, I was able to get through 2 more mags without any failures! The DD bolt in BCM carrier gave me 0 failures through the first mag.

Today I used only Federal XM193 and did a few runs with the bore snake. Otherwise, nothings changed. Before swapping bolts, I did try a new gen2 30 pmag-which didn't help. When I switched back to BCM bolt and carrier, the issue came back. It may have been wishful thinking, but it did seem better. Here are some pictures (actually mine this time). Thanks to everyone for taking the time to look!


Here is how it looks after the first round goes bang and trigger fails to reset.
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Here are the fired and unfired rounds from the first picture. The dents were not present before shooting.
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This is the same fired case from the first 2 pictures.
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Another common look, different from first photo.
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I loaded 5 total rounds, 1 at a time in the magazine. (2 of 5 ejected) In this picture pointing the muzzle up resulted in the casing falling out free.
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