This skill is most useful with a gun that reloads frequently and/or quickly such as Pistols and Shotguns manufactured by Jakobs. This pairs well with Decepti0n, as the player can reload in relative safety while moving into position for the shot. Using it along with powerful sniper rifles is also a possibility, since it will allow them to kill many enemies instantly on a critical hit.
As the Infinity only has 1 bullet in its magazine at any time, technically making every shot the 'first', the gun synergizes extremely well with this skill. This can make the Infinity an even better backup weapon as it will always have an effective 60-132% damage bonus regardless of other factors.
The 12 Pounder, a Rocket Launcher, also benefits due to a quick reload speed and magazine is always fixed at 1.