The Fastest Gunslinger is an event released on May 12th of 2016. All the tiers requires the player to kill a specified number of enemies (normally or by doing headshots) using only the weapons listed below.
The Spotter's duration is also dramatically decreased throughout the event. This is because they wanted to test the players if they are the Fastest Gunslinger, and by limiting Spotter the players would have to rely upon their reactions.
During this event, Revolver was the most used weapon since it is the only weapon among the allowed weapons that can be bought in the shop.
Freedom Revolver is the second most used weapon in the event, due to it being the first and the easiest to earn prize of the event.
During this event, there's also an increased in players using Stun Grenade, in order to "stop" others from moving, thus allowing them to get headshots easier by getting close to them. Additionally, there's also an increased in players wearing the Ghostbusters Pants to counter being stun by those.