Aha! Haven't got to the root cause but...

by Hoot , Diversityville, Liberal-sota, Thursday, September 06, 2012, 14:15 (4463 days ago) @ Hoot

Found out if I hold the bolt down tight on an empty chamber, the sear trips but the firing pin is not released. Simply releasing the pressure on the bolt lets the FP loose. The cartridges I used, being long, would have exerted enough "back force" to hold the bolt in the tight-down position. Now to find out why it hangs up in the first place...