My idea for this wonderful weapon.

Sergio Six-Shoooter
Like the name says it has 6, six shots.

Pros:
increased damage, 10 to 25 %, maybe?
Quick Draw: increased weapon switch speed to the revolver. 15 to 25% perhaps?
Taunt kill:Trick Shot. Spy flips a coin and then shoots it, thereby making a ricochet attack if there is someone in front of him.
Fanning the Hammer: Press the Weapon slot key to change the firing mode to Fanning the Hammer, which increases fire rate at the cost of the movement speed, nothing major, 10% slower.
Cons:
Slower firing speed(it is a old revolver)
Six shots that have to be put in one at a time. Which is a bit of a problem.