Ruger factory low rings, got knocked on the floor while disassembled and now I don't know which upper half goes where on which bottom half. I should have marked them before disassembly but didn't. Any way to get them sorted out so that they fit properly? Thanks in advance!

Mix and match. They are mass produced products so don't require being matched unless you have lapped them.

You can usually match up the polished shape. GD

I was thinking you could try to see if theres a good match on the first half - there's only two top halves and two orientations each. When you got one nailed then there's only two orientations to try on the other. If you can't pick any difference then maybe it doesn't really matter.

I saw an old guy set the gap on points in a distributor once without feeler guages and he got it spot on (we checked it later).

Nobody under the age of age of 50 knows what you’re talking about! (But us old farts do....)

That's what match books are for