We have experienced that, shooting from our shot shed, which have corrugated steel plates for 3 sides, well shooting at a sand berm only 15 - 20 M away the 45 degree slope of sand with a little smaller stones in it managed to 180 a 18 grain .22 pellet shot by my friend.
There was no doubt what hit the back wall of the shed, and we looked flabbergasted at each other CUZ we did not expect that
I only shoot that short when messing with my adjustable scope rings to get a fairly 0 setting off point, normally i dont shoot shorter then 75 M, that is unless it is windy then i will bite the weather vane and shoot 50 M, but otherwise long balling is my game.
There is a video on youtube, some guy almost shoot himself with a 50 BMG, after first sending the bullet a long way in a safe direction.
Thats damn scary stuff.
Making me freak the hell out when i saw some indoor gun range in the US you can get to rip on a Ma Deuce ,,,, and a M134 too for that matter.
And trust me if i get the chance to pull that trigger,,,, well there will be many USD in my pocket eager to be set on fire.