Thing is, with d20 you could have players run around with Desert Eagles and it wouldnt make any damn differance. A magnum .44 round does about a D8 of damage so it would be the same as a longsword except you dont get to add your STR bonus to the damage. Theyre just as useless as bows and crossbows past level 5-6
Gunfights in games like Urban Arcana(D&D+d20 modern crossover) consists of the participants standing not 5m from eachother taking turns at shooting eachother at point blank range with the occasional:
-He throws a hand grenade at you at 23.
-I only have AC 17 so he hits
-Ok, it does *rolls dice* 29 damage with rephlex save for half.
-Alright *rolls dice* I save so I take 14 damage. Meh, Ive still got 43 hitpoints left.
In d20, melee is the king. Dont remember if melee-attacking an opponent with a gun causes an attack of opportunity though.