Thanks for all the info.
So far I have put ~500 rounds of 115 grain ammo (Winchester, Federal and Remington) through it with no issues (except with aluminum case ammo). It should be broken in reasonably well. I've not tried heavier ammo because I've suspected bolt speed could be an issue.
I have the KAK buffer tube and stabilizer. I did install an NFA tube spacer at the outset. PSA 9mm buffer and carbine spring. I think I can run down an adjustable buffer or at least some heavier ones to try.
The bolt would lock back intermittently when pulled back. Better with new factory Glock mags. But, if it locked back, I could pull the bolt back usually 2-4 more times and it would close. Which I did not like.
One clue I picked up from another post dealt with the clearance for the LRBHO actuator bar contacting the inside of the upper receiver. This may be part of the issue. The actuator bar, at the forward pivot has a sharp 90 degree bend. I've researched other manufacturers that use a similar idea the the actuators on their guns are rounded off.
I also noted that the actuator must be designed to cant out to help lift the bolt catch into position. If the inside surface of the upper is preventing that cant, that could be another issue.
So, before I start radiusing actuators and modifying upper receivers, I am going to see if I can find a couple of other uppers from other manufacturers to slap on to see if the lock back reliability improves when I pull back the bolt.
I'm determined to get this gun working the way it should. It's too damn much fun to shoot!