5/64. Allen key twisted. Added heat, Allen key still twisted. Continued adding heat with a soldering iron until the screw sizzled, still twisted. After 5 Allen keys and no luck I broke out the 1/4 hex bits. Again, plenty of heat but the hex bit snapped flush when I used the ratchet. Next screw I used heat, a shank bit on an impact at medium setting hoping to shock something loose. Back again with a new hex bit on the ratchet and got the same results. These were decent bits too from MAC. I have no idea what it’s locked on there with, but I don’t think it’s blue loctite.

Recommend be a drill bit. I’m just having a hard time drilling through with the steel bits wedged in there.

Cut a slot straight across the head and use a wide flat blade?

I do have a drill press, and I tried using the same bits are used to drill the my stainless steel baffles for my suppressor. The broken hex bit inside the screw seems to be a hold up. I’m applying so much pressure. I’m afraid the bit may snap and slam the broken bit or Chuck down and damage the optic. Of course now that I’m saying that out loud I could just adjust to stop at my drill press so that can’t happen….lol.

I do have reversed drill, bits and extractors. I just can’t get them to bite. Should I maybe try some kind of milling bit? I figure at the very least I can break the head off and get the optic off. Then I could work on the slide.

Oh, I will remember the freezing method though, thank you.

I’ve considered that. I’ve done it in the past and it does work, but I’ve never had luck getting only the screw using the Dremel. These things are tiny.

Carbide cutter to remove broken driver bit, followed by end mill cutter.

So my primary goal was to save the optic. I wasn’t overly concerned with the slide. That did not go as planned. I was able to get through the broken hex bit with the carbide cutter. Then I used an end mill to get the screw heads off the shaft. But the screw heads were still bonded to the optic. Some kind of white substance. Rockset maybe? Tried to chisel the remainder of the head to loose, but it wouldn’t budge. I used a cone shaped carbide bit to remove the heads, but I definitely got some of the optic. I was using a drill press so there was some chatter. it’s not the prettiest. I’ll throw it on one of my beater spare guns and see how holds up. There was enough of the shaft, sticking out of the slide to grab with vice grips and twist out so at least this slide is good.

I've never been in that exact situation but it's a real bitch when you have dumb problems like that which seem to get worse and more frustrating as you go down your list of options.  At least you got it  off.