[malloyd]

One side issue is that even if you can see through the wall, you probably can't aim very effectively - multiple layers of variable composition stuff in a typical wall is going to do rather random things to the trajectory of the bullet even if it doesn't slow it down much. I'd probably make you roll as for a miss (as for Hitting the Wrong Target) - your successful to hit roll allowed you to hit the *wall*, not the guy behind it.