Okay, first off you are not able to tell if you have did it or not, it only shows up in third person mode. So you need system link or live so one of your buddy’s can watch and see if u have did it. You need a rifle and a handgun as well as the bomb. Pull out your handgun fire it begin to reload but then jump and while your in the air switch to the bomb in the middle of reloading your handgun.