wait a second ppl. wut r u saying caleb? do you want to change the gun MODEL or do you want to change the guns STATS. because if you want to replace the gun model, then all you have to do is make a model for the gun on ground, the gun in your hands, and the gun in somebody else's hand. then name them the same as the mdl's you want to replace (gunname_w is on the ground, gunname_p is in your hand, gunname_v is in somebody else's hand), and then just... replace them.
now, yea, if you want that crowbar that was turned into a table leg to do 200,000,000 points of damage in one hit, then you might as well make a MOD, too.