Created for a 17th century flintlock era, Musketeer style setting. There are three main types of firearms:

Qualities

Attachment: Can affix onto a rifle a bonus action.

Close quarters: may be used while a creature is in melee range without disadvantage

Double-barrel: if you attack a creature within 30 feet of you, you may also target another creature within 5 feet of it. If you do you deal 1 damage die fewer to each target.

Flintlock Loading: It takes an action to reload. If you gain an extra attack, you may use an extra attack granted to you by your class to reload a weapon with Flintlock Loading.

Scatter: instead of firing at a single target, these weapons deal their damage to all targets in an area (typically a cone or line) specified by the weapon. The first value is its normal range and the second value is its maximum range. Creatures within the normal range take half damage on a successful save and creatures within the second range take no damage on a successful save.

DC is equal to 8+proficiency bonus (if proficient with weapon)+ Dexterity Modifier.

Massive: can only be wielded by Large creatures or above.

Dual wielding note: Pistols are one handed which means light pistols can be dualwielded. Note that you do need a free hand to reload a pistol however.