Is 3/16" machine screw equivalent to a #10?

A tap will work fine for that, and I wouldn't worry about the difference in size, hand tapping will ream it out more than that, regardless.

That said, don't even think about this if it's a Chinese tap.

I've never seen a 3/16 tap, and it's kinda scary.
Roger that! Good luck @dibbons and report back the results.