Functioned perfectly when a single round was loaded into the chamber by hand. Fired, ejected, and bolt closed.
Not so when loading from a magazine. Bolt will not close completely. Tried 8 different mags. Guessing something is allowing a magazine to rise up and somehow stop the bolts from closing the last less than 1".
Looks like a combination of issues. Small burr on bolt face, and a dried-grease filled bolt (made firing pin extend outward slightly) were preventing cartridges from seating properly in the bolt when fed from mag. Polished extractor a little too.
Rounds feed easily from mag now, and bolt closes. Ran five mags full of ammo through it without issue.