Oh no! What do? Throw the frame away and buy another.
Now hold on! Maybe there are options. Don't abandon hope. You still have a chance this will come out alright with no damage to anything more expensive than a sawbuck.
With a stuck screw sometimes tightening it a fraction of a turn will break the grip and make it easier to back out. Or soak it in penetrating oil to loosen the threads. Or... and be careful with this... blow torch. Apply heat. The expansion and contraction breaks the hold and also breaks down any Loctite that might be in there. I said to be careful not because I am worried you will hurt yourself. Burned skin heals. I am more worried about messing with the temper of the metal. Stainless steel is a bit more forgivable than carbon steel. Try not to get the metal to turn straw or blue.
But these hints are less helpful when you have borked up the screw slot.
This was my plan.
First I would put the grip screw back in the cleaned hole with red loctite on the threads of it. Tighten that down tight to get a good bond. Then I'd back out that screw and hope it takes the escutcheon with it. Sacrifice both. Plan B was to put a screw in part way from the proper side, and put another screw with a hex hole on the inside of the magwell. Both screws touching tip to tip. Then use an Allen wrench from the opposite whole to get the thing out of there.
Plan A worked. But I wish I had tried B first. That solution came to me too late, and if it had been attempted and had worked it would feel more elegant, somehow, now.
If it had failed and stripped the threads in the frame, all is still not lost. You can add metal to the hole with a welder and re-tap the threads. But that skill is a bit beyond me right now.
So, itemized, the methods for removing a stubborn escutcheon that I thought of, in order to escalation to prevent harm are:
- tap it a few times with a non marring item (plastic screwdiver handle)
- tighten a bit first before backing off
- a little heat with a torch
- soak it in penetrating oil for a week with occasional taps
- remove all penetrating oil and apply a little MORE heat
- two screws tip to tip, then spin clockwise from the 'bottom' end
- red loctite on a sacrifical screw seated well inside the escutcheon, back out in 24 hours
- spin it with vise grips
- drill our the escutcheon with plans to perhaps add metal to the hole with a welder and retapping
I don't like the penetrating oil, normally. But I am impatient.