Dept. issue is Winchester Ranger SXT 9mm +P+. If you carry another caliber, the ammo must still be Ranger. I carry a .45 ACP. We do have a clause in SOP that allows for anything short of a tactical nuke during exigent circumstances.
As a commissioned officer assigned outside the agency (P/A Office) I have some lattitude, however. MY XD-40 is stone reliable and dead on the button to 50 yards, with Rem/UMC/180-JHP; and so that's what I carry.
Consider yourself lucky. My dept doesnt issue any ammo, period. We are required to buy our won, and there are no guidelines, other than it must be hollowpoint. For that matter, my dept doesnt issue anything but uniforms, badge, and brass. My vest, my duty gear, my gun, my cuffs, my boots, etc...its all mine, and all purchased from my pocket.
FWIW, I am currently carrying .45 230gr Hydra-Shoks, but am looking at changing to Hornady 230gr TAP when I can find a retailer that carries the full pressure LEO stuff.