Musket:

Holding rightmouse while unloaded will load a bullet from the inventory, similarly to the crossbow.
Holding rightmouse when loaded aims the musket, and releasing fires the bullet. Aim time determines the accuracy.
Reloading takes 1.5 seconds, and aiming for 1.5 seconds is enough for perfectly accurate shots by default.
Firing a musket produces a visible cloud of smoke and the shot can be heard from far away, giving away the user's position.

Ammo:

Standard Cartridge: Deals 16 damage and ignores 10% of the target's armor efficacy.
Hellfire Cartridge: Deals 25% more damage than standard cartridges and decreases the target's armor by 25% for 30 seconds. Found in bastion chests or by trading with piglins.
Enchanted Cartridge: Has 25% higher velocity than standard cartridges and boosts musket enchantment effects. Crafted with an enchanted book and an equal number of gold nuggets and cartridges in a crafting table. Also sold by weaponsmith villagers.

All cartridges can be fired from dispensers.
Cartridges are deflected by breezes and ricochet off of iron golems, dealing only 25% of the damage.

Enchantments:

Firepower (I-V): Increases armor piercing of fired bullets by 10% per level.
Longshot (I-II): Amplifies damage against distant targets. (15-60% bonus at 16-48 blocks, 25-100% at level 2).
Repeating (I): Allows the musket to fire twice per reload. This amount is increased when reloading after a kill.

Gunslingers:

Spawns near outposts and will appear as part of raid waves with the same frequency as Evokers.
Being expert shooters, they have an attack range of 24 and do not cause friendly fire damage.
They retreat when approached and use a sawn-off with less firepower than their main weapon to protect themselves.

Configuration:

Reload and aim time are configurable between 20-80 ticks.
Base cartridge damage is configurable between 12-24 damage.
The damage multiplier of Gunslingers are configurable.

Integration:
(Neoforge/Forge only) If Consecration is installed, enchanted cartridges can remove undead protection.
If Enchantment descriptions (or equivalent mod) is installed, the details of each enchantment will be displayed in-game.
If Useful Spyglass is installed, Muskets can be used with the Precision enchantment for increased damage and zoom while aiming.

Credits:
Cartridge textures, sounds, and smoke particle code from ewewukek's musket mod: https://github.com/ewewukek/mc-musketmod
Reload animations inspired by WinterComputer's resource pack: https://modrinth.com/resourcepack/muskets-and-sabres