Yeah, when it does this, it's very rare. And when it actually hits, that's pretty cool. Last time I saw a Bouncy Digger (Including hit/not hitting), was 2 months ago. I wonder if there's a way to actually tell if something of the like will happen, before you shoot it.
I've seen this happen once before, unfortunately it hit right in front of the enemy tank (mid-long range shot). @_@
I think that the ground has to be relatively flat, and that the shot should hit the ground at an angle that takes it up, so that when it bounces back down it'll only go up and down as the ground has no angles for it to bounce around. Btw, was the other tank already in some sort of a pit? If it wasn't, I'd say you were pretty gutty in pulling off that shot.
He was at the very edge of a shallow pit, yes. As for the rest, it'll be rather difficult for the conditions.