I decide to try to shoot through the 55 gallon steel barrel with a can of concrete. The first attempt was with a 4" 4.4 pound can. The concrete had not hardened and mushroomed the can when it hit the barrel. The mushrooming of the can caused the can to not be able to cut the barrel. Instead, it pushed until the barrel tore. Then the barrel 'jumped' into the air about 6" or so. It was full of water up to that big hole, which means it weighed about 350 pounds. Here is a video (221k MPG) The can put a small dent on the back side of the barrel.