There are three types of weapons that you will find laying in the ground or in boxes you break. They are the lead pipe, gatling gun and flame thrower. Each have their own respective trophies for x amount of K.O's, thankfully this trophy is simply for testing one of them out. In the first stage in which Bryan is the boss there is a Gatling gun in the back of the stage. Pick it up with X, and shoot it at one of the lackeys for a quick trophy.