My idea for stats would be as follows:

The Russian Vulcano

+150% max primary ammo
+30% more accurate
Slight knockback on enemy
-15% damage
-10% slower firing speed
+20% fire vulnerability

Taunt Kill:

Heavy removes the wind turbine-looking thing and thrusts it down.
Same damage set up as the Gunslinger. (gibbing the enemy and then an instant kill)

And maybe the Natasha sound effects?