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

A 3/16 screw is a special size. You won't find it in any U.S. catalog of standard screws, nuts, bolts, taps, or dies. You can have special 3/16-24, 3/16-32, or 3/16-60 taps and dies made, so I have to assume they are/were used someplace. Maybe on guns, as they like to use oddball sizes for some reason. Certainly not on a '60s/'70s Mopar!