AR feed issues

[srfisher3]

I recently installed a new heavy barrel on my AR. I put on a new gas block(GB systems) and a new gas tube. About two weeks ago, I took the rifle to the range for its maiden voyage. The first 2-3 rounds went fine however, the weapon began failing to feed. It would extract just fine but the bolt wasn't picking up a new round. I figured I had missaligned the gas block so I took it back to my house and tweaked it. I fired it at the range today but had similar problems. This time, I was able to fire about 15 rounds without an issue before it started failing to feed. The gas block made by GB systems is now discontinued so I'm hoping its just a poor quality gas block...

A friend of mine mentioned it was possible the new barrel I purchased may have an issue in the chamber. He said as the metal in the chamber heats due to firing, it could be causing the malfunction. I'm looking for some direction on how to fix this myself. Thanks

 

[oryx]

Hard to tell whether it is short stroking from a gas system issue or a mag isssue or chamber issue.
It does sound like your issue did get better when you tweaked your gas block, and being that it is not picking up the next round it may be short stroking. So it maybe the gas block alignment. It may help to chamfer the gas block hole slightly to help alleviate alignment issues.

Hope you getting straightened out

 

[DnPRK]

You have to aligh the barrel gas port with the gas port in the gas block in the left/right and fore/aft directions.

Most people know about left/right indexing, but some don't realize that gas blocks come in versions to be used with and without hand guard retainers. This can cause an 0.030" fore/aft mismatch and partially blocked gas port.