Baseball Riot
16 Achievements
Steam
Baseball In the Face
Get five headshots with a single swing in region 3.
4.6%
How to unlock the Baseball In the Face achievement in Baseball Riot - Definitive Guide
There are a few levels in region 3 where this is possible. I got it pretty easily on the 4th level of the region by aiming up at the angled piece in the upper left corner. The ball should bank to the right and headshot all three guys up top, then hit the angled piece in the upper right corner, bank down to the little angled piece behind the ball canister, then bank left. The fine tuning comes in here to get the ball over the head of the umpire and then to headshot the other two guys.
If you can't get that method to work, here's another option: