Depends on the type of shooting: Bullseye, I'm honestly an 8 or a 9. With a .22 revolver and a red-dot mounted on top I've hit 588 out of 600 in practice and 577/600 in competition--95% or better which, according to the NRA, qualifies as "Expert". Without the dot, I've consistently hit in the 540s--90%.
Action shooting? Probably closer to a 5 or a 6. "Combat Accurate", perhaps--I can draw and fire on a 3-second turning target all six shots out of my Model 10 and keep them in the kill-zone just fine, usually. However, I've seen some of the local IPSC and IDPA draw, move, and fire and land all of their shots in a fist-sized group (or, usually, a 3x5" index card) in much less time (2 seconds or less), and it humbles me. And if I ever need to reload, I'm screwed.
Historical knowledge? Not much...probably a 3 or a 4; there's a ton to know, and I've only been into firearms for a couple years.
Mechanical knowledge? I can watch an animated cutaway of a gun run and understand what's going on, certainly, and I know my way around the innards of any modern S&W revolver (and several pistol models) enough to do some basic smithing, but I won't call myself a gunsmith...probably a 5 or a 6 here.