Logo on the front
Cross section of a gun ( glock would be easy ) bullets labled with things, on back.
Only way I can think of that shows the site (sprit) and a loaded gun, without being cheesy.
With things writen on the bullets, you get res issues. t-tshirts sucks ass, i hate them.
edit. maybe with lines point to the parts of the gun, the trigger becomes post, blahblahblah.
~shrug. i try'd.