Help me before I give up on the Grendel altogether

[rabiddawg]

Here is my story.

Alexander arm built rifle. Ran fine for several years then developed an intermittent problem like you described. I tried everything. Different mags, cleaned and recleaned, changed ejector and extractor just in case. Then one day I noticed a bit of smug around the gas block. Gunsmith friend said it was normal but I changed the rollpin type block to a split style adjustable and solved the problem.

As I was adjusting the gas I actually duplicated the problem. Without enough gas the bolt doesn’t travel far enough back to pick up the rim of the case. As it goes back toward the chamber it slides the round with it until it jams. As I added more gas the gun picked up the round and fed fine. The I tried to drop the empty mag and it wouldn’t fall. Turns out I was still under gassed and the bolt was catching on the mag not on the bolt catch. Another turn or two ( or click) and it was up and running til this day.