Non-automatic pistols now do double damage. Their attacks have a much better chance to disarm opponents, and may even cripple a limb.
Ranks 2 and 3 each add 25% range, for +50% total. Rank 4 gives a 6% chance to disarm. Rank 5 increases this to an 8% chance to disarm, plus adds an 8% chance to cripple the limb you hit. In addition, if Nuka-World is installed, Gunslinger now becomes a crafting perk, mainly required for certain upgrades to the Western revolver.
In Fallout 4, all automatic pistols are affected by the Commando perk rather than by Gunslinger.
In Fallout 4, plasma thrower with pistol grip is affected by Gunslinger perk instead, even though it fires automatically.
In Fallout 4. the third rank of this perk adds an astonishing amount of range to energy pistols. This causes both the laser and plasma pistols to have a significantly longer effective range than that of their rifle counterparts.
In Fallout 4, the crippling effect of the final rank affects all weapons.