Set it up on a mill, drill/tap a set screw through there on an angle. If it breaks into the threads, clean up the threads. Then take the set screw out and relieve it so it doesn't affect the threads. Loc-tite for good measure. Then get back with us if/when it breaks again. I'd be curious how long it holds up and wouldn't be surprised if, with some thought, it turned out to be a non-issue.
Can always make a 22 receiver out of it, but that's no fun.
