Originally Posted by PghJim
One of the interesting things about the 357 sig HST is that the exit hole on the first jug and the entrance hole on the second jug indicated a bullet diameter significantly bigger than the final expansion size. If you bend up the pedals the bullet would be over an inch in diameter. Evidently it completed its expansion in the second jug because the exit hole on the second jug was smaller and the same size as the entrance and exit holes on the third jug. One thing we do not always think about when we look at final expansion is that for a part of the bullets trip it expanded up to, and maybe over, an inch and then bent back to 0.61"
JHP's fully expand within 2" or less of penetration normally, at handgun velocities.
What occurs is that the exit on the milk-jugs in the front of the stack is larger because there is more velocity at impact, thus there is less stretching and more tearing. Think about a piece of paper shot with a .45 vs one shot with a .223. The .223 holes are cleaner, and larger in diameter compared with the projectile that made them.