What to do?

[ithacaartist]

Aha! My suspicions are borne out by the pics and further description. Dale, your guess is exactly valid, lack of "education" notwithstanding, and your analysis of how the roundness of the sear's corner causes the problem is spot on! The corner of the striker's latch lug doesn't look all that healthy, either. That's it: blocked by the safety bar, but also set up to fire when the trigger is pulled. The angular foibles of the corners combined with the pressure of the firing pin spring make it so that the safety bar is all that's keeping it from firing. Release the lever, boom.

I spy the marks of a file, I think, on the rounded corner on the sear bar. The side view shows how much meat was removed, which allows the sear to be unlatched relatively early when the trigger is pulled. Too much may have been taken off for the part to ever work correctly again, unless built back up with a little TIG welding, or other compensatory measures taken with the remainder of this system.

Tom Heller can probably better make this call, but there may be enough material left to dress the corners again and re-establish the proper angles and smooth crispness. If not, viable replacements for the sear bar and striker would seem to be the fastest, most effective way to get 'er going again, and very likely he can fix you up with what you need.