Reload Score: 1

Misfire Score: 3

This item is designed to combine the Artificer's Infusion ability with Eldritch Cannon activations. One Cannon can hold traits from either the Infusion list or the Eldritch Cannon activation list, or a combination of both. It can not be imbued with the same trait twice and can contain up to two traits. 

Using a series of levers, the Pocket Cannon can switch between Infusions and Eldritch Cannon activations at the cost of one round of combat, or 6 seconds, during which time the wielder may not take reactions and automatically fails concentration checks. Pocket Cannons can only hold traits that affect damage or change damage type. The traits imbued in a Pocket Cannon can only be removed and replaced at the time an Artificer raises a level.

Ranged attacks are made with DEX + Proficiency. Damage per shot is 3d12 + INT Bludgeoning.

This item can serve as an Artificer's Spellcasting Focus.

Reload. The weapon can be fired a number of times equal to its Reload score before you must spend 1 attack or 1 action to reload. You must have one free hand to reload a firearm.

Misfire. Whenever you make an attack roll with a firearm, and the dice roll is equal to or lower than the weapon’s Misfire score, the weapon misfires. The attack misses, and the weapon cannot be used again until you spend an action to try and repair it. To repair your firearm, you must make a successful Tinker’s Tools check (DC equal to 8 + misfire score). If your check fails, the weapon is broken and must be mended out of combat at a quarter of the cost of the firearm. Creatures who use a firearm without being proficient increase the weapon’s misfire score by 1.

Backfire. When making an attack roll, if the dice roll is equal to a 1, the weapon backfires, inflicting half the attack's damage to the wielder. 

Possible Infusions:

Enhanced Weapon

This magic weapon grants a +1 bonus to attack and damage rolls made with it.

The bonus increases to +2 when you reach 10th level in this class.

Enhanced Arcane Focus

While holding this item, a creature gains a +1 bonus to spell attack rolls. In addition, the creature ignores half cover when making a spell attack.

The bonus increases to +2 when you reach 10th level in this class.

Radiant Weapon

Prerequisite: 6th-level artificer

This magic weapon grants a +1 bonus to attack and damage rolls made with it. While holding it, the wielder can take a bonus action to cause it to shed bright light in a 30-foot radius and dim light for an additional 30 feet. The wielder can extinguish the light as a bonus action.

The weapon has 4 charges. As a reaction immediately after being hit by an attack, the wielder can expend 1 charge and cause the attacker to be blinded until the end of the attacker’s next turn, unless the attacker succeeds on a Constitution saving throw against your spell save DC. The weapon regains 1d4 expended charges daily at dawn.

Repeating Shot

Item: A simple or martial weapon with the ammunition property (requires attunement)

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 it.

If you load no ammunition in the weapon, it produces its own, automatically creating one piece of magic ammunition when you make a ranged attack with it. The ammunition created by the weapon vanishes the instant after it hits or misses a target.

 

Possible Eldritch Cannon Activations: 

Flamethrower

The cannon exhales fire in an adjacent 15-foot cone that you designate. Each creature in that area must make a Dexterity saving throw against your spell save DC, taking 2d8 fire damage on a failed save or half as much damage on a successful one. The fire ignites any flammable objects in the area that aren’t being worn or carried.

Force Ballista

Make a ranged spell attack, originating from the cannon, at one creature or object within 120 feet of it. On a hit, the target takes 2d8 force damage, and if the target is a creature, it is pushed up to 5 feet away from the cannon.

Protector

The cannon emits a burst of positive energy that grants itself and each creature of your choice within 10 feet of it a number of temporary hit points equal to 1d8 + your Intelligence modifier (minimum of +1).

It’s up to you to decide whether a character has proficiency with a firearm. Characters in most D&D worlds wouldn’t have such proficiency. During their downtime, characters can use the training rules in the Player’s Handbook to acquire proficiency, assuming that they have enough ammunition to keep the weapons working while mastering their use.

Notes: Ranged Weapon Attack: Bludgeoning, Damage: Bludgeoning, Artificer, Artificer, Range, Ammunition (Firearms), Reload