Lifelong dedication to any weapon can yield results. Firearms and bows are no different.

Missile Art

Starting when you take this subclass at 3rd level, you may now consider one type of ranged weapon that does not have the thrown or heavy properties of your choice as a monk weapon. You gain proficiency with the chosen weapon, and proficiency in tinkering. If you do not already have the weapon you've selected, one is given to you.

Also, you may draw or holster two weapons in a turn without requiring an action.

Missile Mastery

At 6th level, you no longer have disadvantage when targeting enemies who are within 5 feet of you or who are prone. Also, you may use your Deflect Missiles reaction on any ranged weapon attack as long as you see the creature making the attack. If you reduce the damage to zero, you may make an attack with your weapon against them.

In addition, you gain new ki abilities:

Smooth Is Fast

At 11th level, you gain another extra attack when using ranged attacks you are proficient in.

Mind of the Sinless

When you reach 17th level, your skill and speed with your weapon have become nearly unfathomable. Unless you are firing beyond your weapon's maximum range, or are both blinded and deafened, you ignore disadvantage to weapon attacks you make with ranged monk weapons.