i've just found this outside of the Shrouded Bunker....
[media]http://www.youtube.com/watch?v=pU73h_Ej3QE[/media]

Nice one! I discovered that after I got the crossbow with the exploding bolt ammo. All you do is shoot it up in the sky and it stays there forever. There are other guns that do it also. I wonder why?

oops =))...but i wish the pop rocket or the electro bolt could stay in there