I wish I had seen this when it was up on MCB. I'd have bought it instantly. Good snag PJ. That's a very visually nice Sterling. Once it's running well it should be AWESOME. It almost sounds like it's just badly out of time - like the sear is pushing the carrier back, or the sear spring is too hard. Could be a few things. Try cocking the gun with the grip frame off and watching if anything's rubbing or sticking.
PJ, if you ever want to sell it or if you do take blackrain up on that refund, please keep me in mind.
...'cause bandaid's stuck on me!