Well this is the 2nd 450 I've built. The 1st one was perfect the 2nd not so much.
Bolt and barrel are budget buys from Davidson's defense.
16", carbine length barrel, surplus GI mags. Nothing fancy.
Hand cycles perfectly
With mag inserted, bolt doesn't cycle back, at all after its fired. Hand cycle to clear the chamber and strip the next round
Insert mag, charge the handle then drop the mag, bolt cycles and ejects.
What I forgot, old man brain fart, was to test with empty mag to see if bolt catches after the single round cycles
Not sure if this is a gas issue, mag issue or combo of the two