I think my head is going to explode............(updated, sort of, post 32)

[Stevo]

It's still not right. Better, but not consistent.

From marks on the stock's paint it looks like the inside of the stock cap was banging up into the gas cylinder. I relieved that a bit and will see if it makes a difference.

As per your earlier suggestion, I've also taken the handguard off and will shoot it to see if it's the stock causing the problems.