I logged onto DayZ today so see three zeds camping at the bottom of the ladder. I then equipped my fire-ax and climbed down. The first one went down on the first shot, the second zed would not be hit I was forced to swing several times before the game registered a hit. The other Zed was stuck in a wall.
Later I happened to come upon a military base where a zombie aggroed through a wall. I quickly took out that zed with the fire ax and snuck up on another hoping to hit it.. I must have swung well over 15 times trying to hit it. I tried running both clockwise and counter-clockwise, I tried standing still and it would not register the hit. Eventually I killed it after getting fractured and bleeding.