Quote Originally Posted by CrAzYLoCaL View Post
No, no, and no. ARs have a gas system, and that gas system is what works the action back and forth giving you an evil and terrorizing semi-automatic feature!! All that hot gas from the fired cartridge gets sent down the barrel...up the gas tap... then it 180's right back to your face... dumping all that hot gas in the action. That is why they get so dang hot. Don't forget to tie your shoe laces tight! Happy shootin'
I have no idea what your shoelaces comment is supposed to mean...

The gas system was my first thought, too - see post #4.

But that doesn't explain hot brass from lever-action rifles.