I never had any respect for the 5.56, especially after seeing a group of SPs trying to dispatch a small black bear with one. The bear had wandered into the housing area and the cops decided to kill it. They fired all 50 rounds that they were carrying, hitting the bear 38 times. It continued running and eventually went up a tree. The cops finally called in and had someone bring a 12 guage.
I've seen a piece of brush the size of a pencil deflect a 5.56 bullet way off target. It doesn't have the mass to penetrate at any distance. Once you get out several hundred yards you have the same bullet size and velocity as a 22 magnum.
Don't even get me started on the 9mm.
They can all be deflected. I saw a photo of a .30 caliber cutting a playing card in half. The path of the bullet was deflected upward. I also saw the video, "Dangerous Weapons". It showed a .50BMG round deflected by a one inch tree branch.