Follow up to the original thread... I did have a small issue. That issue was that loaded magazines would not seat in the gun.

I think I figured it out -- my buffer spacer that I made was too thick. On paper everything added up correctly but in reality I forgot to account for stuff, not sure exactly what, but I think it's fixed now.

When I pulled the charging handle all the way back it didn't allow for a full rear travel. Lock back was actually catching on the carrier not where it was supposed to be. As a result the bolt was interfering with the magazine, or rather the ammo in the mags.

I ground down my buffer shim just enough to allow more rearward travel and now everything is catching where it's supposed to. I will try to do some testing later today, but I'm pretty sure I figured it out.