I am a big fan of J-B Weld. Learned about something like it when I was in the military. The stuff we used them was called Devcon and we used it for everything. If it is good for a 50 million dollar aircraft....... So J-B Weld is my go to for most small repairs. I probably would not have bothered with a gunsmith. Most are just parts replacers. I would have taken it to a real weld shop or a machine shop for a repair like you are attempting. That said, good luck with your endeavor and keep us posted!

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USMC 69-93 Combat Pistol Inst.