I just put one of my boxlock ejectors (an old Browning B-SS) together. Its ejectors do stand proud, after I've pushed them flush, when I mount the barrels, but they have no problem camming over the extended firing pins when I reassemble and close the shotgun. You were able to do it a couple of times before this problem appeared, though?
Are you remembering to keep the opening lever fully to the right throughout the entire re-assembly process?
And... There ought to be a screw between the two protrusions on the underside of the barrel. It's a fore-and-aft travel-stop for the ejectors. Is it sitting flush with the surface it's inlet into, or is it standing proud a bit? Because maybe your ejectors are sticking out a bit too much after you went through your takedown exercises. The screw might have backed-out a bit.
Note that I'm pretty new at this, too. I've had my share of DOH! moments with my shotguns.
Last edited by Fudd; 12/13/23 07:16 PM.