What sizes of taps and screws do I need to do a screw build?

My cheapie Yugo is turning into a test bed.  It will have u-drive screws, button head screws and maybe even rivets.

Might as well try it all...

I purchased a 10/32nd tap (#21) when I initially had plans on doing a screw build.  For the u-drive, I ordered #10x 3/8", which have a perfect head size for the Yugos, but in my opinion, not for the Romy kits -- these I plan on using the #8.  For revit sizes, you wanna go 5/32"x3/8" for the front trunion and trigger guard revits and 3/16" x 1 1/2" (turned down a bit) for the rear trunion.

The trigger guard takes an 8/32 tap (#18 drill bit, IIRC), the trunion and rear block screws are 10/32.

I did two screw builds when I first started building (Hungarian and Romanian), and I found that 8/32 screws dropped freely through the triggerguard holes.  No drilling or tapping was necessary, and I fastened them with 8/32 nuts on the inside.

Have since disassembled them both and rivetted them properly.  By all means try the screw build, and have fun with it, but you may find rivetting with the tools currently available to home builders is easier than screwing.