First off I just have to say there is such a great wealth of knowledge here and I appreciate everything that's been posted in here.
Dad bought this upper and I have spent the last year dicking with it trying to make it right. Having done some aggressive research I came across the gas tube length and have determined, among some others , what the problem seems to be with this gun... and I believe it directly kings to the length of the gas tube.
Currently the tube does not project into the cutout with for the bolt retainer , so an armalite gas tube will be on order.... secondly the gas port on the 20" barrel was only .069".... port was opened to .095" by me and it started cycling to what I would say is 80% of the time.
I'm a reloader and have been shooting my own reloads as well as about 2 boxes worth of winchester through it. Same results . My loads are 25.5grns of 4320 with sierra 150gr. Bullets. These are all hand metered loads so I know they are extremely consistent.
This was a "budget build" so the recoil system is what came out of the utg ar308 a2 stock box. I have been reading that I may need to adjust the buffer weight to 5.4ounces? And what spring would be ideal? The rest of the lower is dpms parts on a 80% lower. I have a second lower configured exactly the same and get the same issues across the board.
Any and all advice is welcome. I understand from the get go this is a hodgepodge . Thanks guys