How NOT to shoot a US 57mm cannon...dont stand behind the breachblock or you will learn to fly. The funny thing is the rest of the gun crew dont look all that concerned.

http://www.boreme.com/boreme/funny-2005/extreme-kickback.php?gobackto=funny-collectionsqqmishaps-p1

MuhAhahhahaHa..what a maroooon..

you know though after watching it....I really think the cannon malfunctioned. I didnt see the breech block close, he was having trouble getting the shell to seat, slammed it in twice then BOOOOOM and the now empty case also comes out of the gun during recoil at high speed.