Repeating Shot Pistol

Ammo: firearm bullet [5.5e]

Vex (Mastery): If you hit a creature with this weapon and deal damage to the creature, you have Advantage on your next attack roll against that creature before the end of your next turn.

This magic weapon grants a +1 bonus to attack and damage rolls made with it when it's used to make a ranged attack, and it ignores the Loading property if it has that property. If the weapon lacks ammunition, it produces its own, automatically creating one piece of magic ammunition when the wielder makes a ranged attack roll with it. The ammunition created by the weapon vanishes the instant after it hits or misses a target.

Ammunition: You can use a weapon that has the Ammunition property to make a ranged attack only if you have ammunition to fire from it. The type of ammunition required is specified with the weapon's range. Each attack expends one piece of Ammunition: Drawing the ammunition is part of the attack (you need a free hand to load a one-handed weapon). After a fight, you can spend 1 minute to recover half the ammunition (round down) you used in the fight; the rest is lost.

Loading: You can fire only one piece of ammunition from a Loading weapon when you use an action, a Bonus Action, or a Reaction to fire it, regardless of the number of attacks you can normally make.