Yeah, I concur with Charlie. Some of my gunners used to do great [like 100% first round hits] in UCOFT (an old gunnery simulator that the US Army used back in the 80's) but then would only qualify as QUALIFIED on Table VIII.
Using a joystick is more like firing from the commanders position (at least in an M1) than from the gunners position. Also you don't get that nice shove to the forehead when you fire, you don't get to smell that burnt ammonia from the spent casing and you get to use both eyes in the game, (the gunners sight in the M1 is useable with only one eye).
Combine the cramped area, the smells (burnt ammonia, farts, BO, diesel, hydraulic fluid, spilled MREs) your legs falling asleep (remember its cramped) the bumps and bruises you get from being smacked around by your young smartass driver, the constant hiss of the intercom in your ears through your CVC (Combat Vehicle Communications - the helmet that Tankers wear in a tank) which is rubbing your head and ears raw from wearing it so much, (plus it stinks from your nasty head), and for some reason not all of your shots hit first time. I can't for the life of me figure out why though.
If you can integrate all of that into the simlation and still hit 100% go see a recruiter and tell him you're the shiz-nit and need to get into the Army ASAP!