Hey Steve and Jim, thanks for the replies.

Regarding Steve's input:

1. Gun is clean and well lubed. Think Private Pyle and his Charlene fetish. I use Wilson Combat grease on everything except the op rod, which gets lubriplate. I've wondered about the ammo. I have Lake City and some 3rd world NATO stuff, cant remember when I acquired the NATO stuff in relation to when the problem started, but I will definitely take a variety with me next time I go. Haven't paid attention to the clips until lately. Read about one brand that is junk, I dont have those. Last friday I used AEC clips with the NATO ammo. No luck. There is a thread on CMPicon about AEC clips, one guy says they're junk, other guys say they're great. I have other brands an will try them.
2. Plug is unvented.
3. I pass the 60 deg tilt test with flying colors.
4. Didnt know about the roll pin. Ill check it.
5. Plug is tight. Threads are clean, and I have the wrench and the holder that fits on the cylinder lock.
6. Spring is greased. I think the op rod is clean on the inside, but ill check it again.
7. I replaced the op rod spring with an Orion stainless steel spring. I'm making a fixture to measure spring loads on the new and original springs.

Per Jim's comment, so that gouge in the bore is normal and in fact necessary? Great! The gas cylinder seemed to be in nice shape otherwise with a lot of life left.

I'm gonna try and get out again this Friday and try different ammo and clip combos. If its the ammo, I guess that gets relegated to my Springfield. Thanks again for the help guys.

---------- Post added at 06:09 AM ---------- Previous post was at 06:07 AM ----------

Oh yeah, I forgot. Gas port is clean. Shank of a #47 drill fits, a #46 doesnt.