Hi all.
Found my way here on a recommendation from another board.
Put together a thumper that won’t cycle ..so far. Cycles and ejects by hand fine.
Relevant's below.
Davidson/aero XL upper 16” barrel and gas system. Aero lower /mil spec lpk ,Lancer mag with Tromix follower and half moon mod. A2 stock/ spring 5 oz. buffer.
Using hornady black 250.
Edit to add, BCA barrel and Toolcraft BCG.
Where I am so far with troubleshooting.
First thing tried was to add a BCM extractor spring.
Eliminated stove pipes but still no cycle or lock back.
Went through gas system, block port is aligned, no blockages, gas key on carrier is tight, gas rings on bolt are correct.
Barrel port measured .066 from factory ;8.375” from barrel crown. I opened port up to .078.
Third range trip with larger port size gave 1 bolt lock back on half dozen or so tries. Sometimes she will chamber second rd, sometimes will not.
I believe the barrel port may still need to be larger.
All suggestions or input appreciated .
RT