Handgun

Handgun
The Handgun is a starting weapon that you obtain from joining the game, along with the Sword. It deals intermediate damage to zombies and have no recoil or reloading, with the exception of a >1 second cooldown period.

Trivia
The handgun is currently based off of the Desert Eagle, which can be filled with .50 AE.

However, judging by the low damage it does, I would say it is probably filled with .357 Magnum. (The smallest and weakest type)