It’s an M1 Garand rifle, US standard issue infantry rifle during WW2 and the Korean War. It’s loaded with an 8-round clip. As the last round is fired, the empty clip (the black square thing you see flying out of the reciever) is ejected along with the last empty cartridge case and the bolt locks in the rearward position. The shooter then inserts a fresh 8-round clip into the weapon and moves the bolt forward.
If you watch the likes of Saving Private Ryan and Band of Brothers, you’ll hear the distinctive “ping” of the empty clip being ejected plenty of times.
Top Comment: The final nail in the dubstep coffin.
RichVR
4124
Please correct me if I’m wrong. But that’s an M1, right? If I remember correctly, the sound of the clip being ejected and hitting the ground was often a signal to the German troops to attack the unfortunate that was trying to reload. It got to the point that US troops would go into battle with empty clips and throw them at the ground when they still had a full clip so as to cause mayhem.
As I said, I’m probably wrong but it sounds like it’s true.
Edit: oops
One of the best things about the original Medal of Honor was the sound of that gun.

… I haven’t used this thing in, like, 5 years.
Ah, thanks! I’d recognized it, but never realized the clip was ejected like that. Sort of silly, since I knew you popped the clips in, and it has to go somewhere…
Harkonis
4128
wow, must know story and end! ;)
To what are you referring?
MrCoffee
4131
I wait and wait for his finger to get smashed but it never happens.
Harkonis
4132
that really looks like some kind of super powered Hulk stomp
In case you were wondering why not to step behind a horse (let alone go for a surprise grope):

Erik_J
4134
You mean why not to clap a horse on the ass?
gmonkey
4135
That probably means some broken bones for the idiot, at the very least. Luckily, he doesn’t seem to have been hit on the head.
What exactly was his goal in doing that? Trying to get the horse to rear?
Erik_J
4137
Or make it prance instead of just step. It wasn’t high-stepping enough?
Tankero
4138
I think it’s someone with mental problems.
And a valuable lesson was learned on that day.
hong
4140
I think he was, actually. Broken jaw or nose.