Easy peazy so long as they mill the slide tight and mill in recoil lugs. Seen a lot that don't.
FWIW, you can take or mail the slide and optic to MAC and they will cut the slide specifically to your optic. No gap. No wiggle.
What slide? Personally, I'd go with someone that has a solid track record over the closest one. That said, Mac Defense is solid. Not "close to Newnam," but not far either. Just expect a wait to get it back.
Flying Monkey Firearms in Lawrenceville is another option.
Tldr
Of course you can make damn near any simple tool with a mill, lathe, welder, plasma cutter, bench vice, calipers, etc. Sometimes it's nice to just buy a proven tool.
And rearward force is very different than lateral and rotational force.
Nope. Reaction rods are stronger than the bolt lugs on an ar bolt and the reaction rod locks into the barrel extension with the intent wo torque the firearm, not just fire it.
Always a fan of tinkering. But some thoughts...
1. Replace the broken drill bit with a set screw and loctite it in place.
2. I wouldn't remove spring tension on the mag. As it breaks in, much more likely to get failures as the spring weakens. Granted, cheap fix, but kinda goes against the...