this rifle is cursed.
Just to go over this: DPMS receiver, 20" .308 barrel, rifle gas system, Superlative adjustable gas block, I bit the bullet, found a H4 buffer for a decent price and it's paired with a extra extra heavy buffer spring. I took it out early in the week, and with the gas block venting at just shy of its complete capacity I got 22 rounds with no problem, then it started stovepiping. With the empties ejecting at 3 o'clock.
Thinks I, 'Maybe it's when it gets dirty that it starts it again', so when back home cleaned it thoroughly and lubed, then today took it to the range to try again.
Nope. Same problem from the start.
So I'm out of ideas. Other than finding a open-minded priest.
Added:
Had a standard gas block when all this started.
I did get a new extractor/spring set, as a bunch of people mentioned that as a possibility.
Ejector is the same, but has been checked on function.
Works great bare, but add the backpressure of a can and this happens, with all indications being overgassed.
I have built several AR15s in the past, none of them had such a problem.
Blarg, dammit.
2nd Added:
Obviously there's something about adding the can on that's triggering this. Annoying as hell.
And to Anonymous, somebody mentioned the gas port itself possibly being the problem, and it's on the list to check soon as I have time.
Again, folks, thank you for the comments, personal 'This happened', and other information