Shooting through a tape measure

They shot .22 and 9mm handguns at a rolled-up steel tape measure. The bullets hit near the outer edge and did not go all the way through. Then they shot a .40 caliber handgun round. It hit in the center, and went through. Their conclusion was that only the largest caliber was capable of penetrating. What they failed to notice, however, was that the two smaller rounds that hit near the edge went through the thin outer casing and were stopped by the edge of the rolled up tape inside, effectively about an inch thick of solid steel. The .40 caliber round hit in the center, going through both sides of the outer casing, and through the empty "doughnut hole" in the middle of the rolled tape. If the .40 caliber round had hit near the edge, like the .22 and 9mm rounds, aligned with the steel tape inside instead of the center void, it most likely would not have gone through, either. So, the "myth" that a tape measure can stop a bullet was not necessarily busted. It depends on where on the tape measure the bullet hits. To have conducted the experiment properly, all three bullets would have to have hit the tape measure in the same place.