It seems to me that SRAM used not rivet to hold all the cogs in one place, but long screw. This screw looks like a hex one, but I tried hex keys I have and I didn't find a match. Unfortunately the head is so small I cannot be sure it is hex in the first place (and not for example pentagonal).
So my question is am I correct with the "screw lead"? If yes, is it a hex one indeed? And what size?
I am asking to avoid drilling it through. Screw is always nicer to work with also because I can screw it back.