Short Cycling AR15 fixed

[nate76239]

I thought I would share this to help others diagnose a similar issue with their rifles. Maybe some others could also share their symptoms and solutions to create a troubleshooting thread. I built this upper from individual parts it is a 16 inch 5.56 barrel with carbine gas system. The remaining parts arrived Monday 1/19 and I was able to assemble it and go to the range that day. I fired 60 rounds of American Eagle .223 55 grain. Sometimes it would not load the next round but did eject the empty case, this happened about 5 times. I could see the gas tube was getting dark black fouling just as it leaves the gas block. A few days later I bought another gas tube from a local shop and replaced the part. Went back to the range Friday and it ran flawless 40 rounds of the same American Eagle .223 and another 40 rounds of American Eagle XM193 5.56 ammo. The first couple pictures are the bad gas tube after it was removed and you can see the dark fouling where gas is escaping.




This next picture is with the new gas tube after 80 rounds of use and it looks a lot cleaner as there is no gas escaping.

[arnie19]

I wonder if any one will try to put a groove in the hole the tube fits in to use a rubber o ring to seal it .

[ar15barrels]

Leaks at the gas tube usually self-seal with use.
The carbon builds up until the gas is closed off and there is no more gas leak.
It just takes a few hundred rounds to occur naturally.