The heavies are usually dumb enough to come over to pick up your backpack . . . Hehehe . . . You can totally defuse even the heaviest of offensives with this strategy. Use your speed to get right up on them. You'll know you're doing it right when Soldiers and HWguys are running away from you, a lowly engy.
Nobody really uses it to get ammo.
Even fewer know how to use it best. Very few engys know that you can hit your dispenser with the wrench and load more rockets into it. It can hold up to 300 rockets. Don't build it so it blocks a long hallway, it'll get shot. Also on the ground floor of the ramp room, just to the right or left of the narrow hallway that leads into the rr.