Pretty much taking a new pistol model, make it look like a police grade pistol, texture it black, use a similar script the the Lupara shotgun, where after 2 shots, it stops to put new shells in, but like someone has already said, make a block model that falls out of the gun, then a new one slides in and for the clip, like every other gun does when you shoot, and the empty bullet casing comes out of the side. Then set the shots before reload to 6 or 8 shots. You could probably directly ask the person who made the Lupara (Shut up I forgot who it was) and maybe after a couple months (1 month to make it, 1 month to consider making it) you'll get something. Of course I don't know for sure but its worth a shot.