Source: Tasha's Cauldron of Everything

You have a quick hand and keen eye when employing firearms, granting you the following benefits:

• Increase your Dexterity score by 1, to a maximum of 20.

• You gain proficiency with firearms (see “Firearms” in the Dungeon Master’s Guide ).

• You ignore the loading property of firearms.

• Being within 5 feet of a hostile creature doesn't impose disadvantage on your ranged attack rolls.