It fires AP, HE, Tracer, and the handy-dandy all-purpose anti-personnel canister round which looks like a big shotgun shell and is the one load that probably settled the issue on Guadalcanal, thanks to its ability to nip 13 Japs at a time in the bud.
Should you need one of these funk'o'ramas, you'll find it parked in front of old Legion and VFW posts, next to the Veterans' Memorial in Anytown, USA, or at the odd yacht club that uses it as a starting gun.
Our COMBLOC adversaries also have a way cool quad mount radar-linked 37mm AAA version that is the bigger brother to the 23mm, and the smaller version of the 57mm
BTW, 37MM = 1 7/16" = pretty darned hefty. IIRC, The handgun version called the "Big Momma or Supreme Court Judge" has been recalled, as it caused damage to purses of CCW holders and unacceptable collateral damage in courthouses.
http://en.wikipedia.org/wiki/37_mm_Gun_M3
That 37 mm sounds great; I need one that’ll fit in my pocket.