Today I received a pair of BRNO steel rings for the CZ 550 (or ZKK-600 series). When I looked at them, they had two of the screws snapped off in the holes through the rings.

Years ago that would have really ticked me off, but as I only paid $16 for the rings including delivery by priority mail, I just grinned.

Here's how I fixed them, and it took way less than 5 minutes, so I wrote it up in case anyone else out there can use the info. It might also work on a lot of other makes/kinds of scope rings:

"You likely already know this, but just in case you don't....when someone
loses a couple of the screws for those metric threaded BRNO rings, he will
usually not realize they have metric threads....so he will try to use SAE
6-40 fine screws in them. Doesn't work. The 6-40s will hang up after going into
the rings about 3/16", and when they do, he will often try to force them the
last 1/16" into place. That often snaps them off in the rings.

To get the broken stubs out, just put the rings in a vise under a drill
press, and drill straight down clear through the screw stub from the top,
using any one of a #50, #51, or #52 size drill. I prefer and use a #51.

Because the drill will be rotating the same way the screws turn into the hole, the drill will
usually "catch" in the stub just enough to turn it most of the rest of the
way through the rings and almost out the other side. It helps to drill
slowly, but with a bit of pressure on the feed. That helps the drill have
more friction as it goes through the screw stub. Anyway, if the screw
doesn't go clear through the hole in the rings, it WILL be sticking out the
other side at least half way by the time the drill gets through it. If
that happens, just grab the end sticking out with a pair of tweezers and
turn it the rest of the way out. Voila!...an undamaged hole with nothing
stuck in it!

Then, if a person doesn't have access to a ready supply of the correct tiny
metric screws, all he needs to do is run a 6-40 SAE fine tap through the
hole. It will provide PLENTY of grip even though re-cutting the threads, and
then he CAN use 6-40 SAE fillister-head screws, which are very readily
available."

Probably lots of other ways to do it too, but this works just fine for me and IS quick.

Best wishes, y'all