Modifications

You can add very basic modifications that don't take up much room or space on your firearm, as they are just simple tweaks.

Iron Sights

Requirements: 1st Level

Your firearm gains a +1 bonus to hit. 

You can learn this modification up to 3 times, and for each time you have learned this modification beyond the first, the bonus increases by 1.

Heavy Caliber

Requirements: 1st Level

Your firearm gains a +1 bonus to damage. 

You can learn this modification up to 3 times, and for each time you have learned this modification beyond the first, the bonus increases by 1.

Tune Up

Requirements: 1st Level

Your firearm misfire score decreases by 1, to a minimum of 1. 

You can learn this modification as many times as you want, and for each time you have learned this modification beyond the first, the bonus increases by 1.

You can modify the barrel of your gun, typically to alter range or volume of the weapon.

Silencer

Requirements: 1st Level, firearm must not have the heavy property

Your firearm is no longer loud. Your firearms normal range also increases by 10 feet.

Amplifier

Requirements: 1st Level, firearm must not have the light property

You put a wide cone on the end of your gun, making it extremely loud. You can give yourself advantage on speech checks you make to intimidate people.

Long Barrel

Requirements: 5th Level

Your firearms normal and far range both increase by a number of feet equal to half of the guns base normal range.

Sawed Off

Requirements: 5th Level

Your firearms range decreases by 15 feet (minimum of 5 feet), but you no longer have disadvantage when shooting your firearm as a result of a hostile creature being within 5 feet of you. 

Bullet Pathing Corrector

Requirements: 9th Level, +2 to misfire score

Whenever you miss an attack, you can choose to target another creature within 15 feet of the original target. You can use your bonus action to reroll the attack, otherwise it uses the same attack roll. You can only use this once per turn.

Acid Hose

Requirements: 11th Level, firearm must not have the light property, +2 to misfire score

You add an alternate fire mode that causes a stream of acid to spray your enemies, allowing you to cast lightning bolt as an action. When you cast lightning bolt this way, it deals acid damage. Once you do so, you cannot do it again until you take a short or long rest. 

You can learn this modification multiple times, and for each time you learn it beyond the first, you have one additional use of this ability. The penalty to your misfire increases by 1 each time you learn this modification beyond the first.

Heavy Barrel

Requirements: 15th Level, +2 to misfire score

Your gun can deal an additional 3d6 damage once per round if you have advantage on the attack. +2 misfire score

You can add a modification to the underbarrel of your firearm, allowing for a wide range of utility.

Bayonet

Requirements: 1st Level, firearm must have two handed property

You can attach one light melee weapon that you are proficient in to the end of your gun. The bayonet weapon retains it’s normal damage die, and you use strength or dexterity on the weapon for attack and damage rolls like you normally would. 

If you make an attack with a firearm with a bayonet on it, you may use your bonus action to make an attack with the bayonet until the end of your turn. If you hit a creature with the firearm before using your bayonet, you have advantage to hit that creature with the bayonet until the end of your turn.

Grapple Gun

Requirements: 1st Level, firearm must not have the light property, +1 to misfire score

You can shoot a grapple hook attached to a rope as an action. Your grapple hook has a range of 60 feet. After grappling something, you can retract it, either pulling it towards you, or pulling you towards whatever you grappled, depending on the size and weight of the object. You can also attempt to grapple a creature this way, they must succeed an Acrobatics or Athletics check vs your save DC. They can repeat the save as an action on their turn, or they are freed if another creature uses their action to cut the rope. If you try to retract the grapple hook while grappling a creature, they make a Strength save vs your save DC. On a failure, they are yanked 60 feet straight towards you, and on a success, you are pulled 60 feet straight towards them.

If the target of an object is particularly difficult, such as it being a small object or moving around a lot, the DM may ask for you to make an attack roll with the weapon to hit it with the hook.

Stabilizer

Requirement: 5th Level, firearm must have the two handed or heavy property, +1 to misfire score

If you have not moved yet and your target did not move on their last turn, you have advantage on your first attack against the creature.

Bipod

Requirement: 5th Level, +1 to misfire score.

If you remain prone for your entire turn, attacks made with the attack action cannot misfire. You can drop prone at the start of your turn if you are not already prone to gain the benefits.

Quickdraw Grip

Requirements: 9th Level, firearm must not have the heavy property

As a reaction when you or an ally is hit by a projectile such as another bullet or an arrow, you can attempt to shoot the projectile out of the air. Make a sleight of hand check, if your check beats the attack roll, you roll damage for your weapon, and reduce the damage of the projectile by the amount of damage you rolled.

Flashlight

Requirements: 9th Level, +1 to misfire score

As a reaction when you are hit with a melee attack, you can flick your flashlight on, temporarily blinding the attacker, giving them disadvantage on their roll. 

Additionally, you can use the flashlight as a bullseye lantern.

Grenade Launcher

Requirements: 11th Level, firearm must not have the light property, +2 to misfire score

You add an underbarrel attachment to your gun, allowing you to cast fireball as an action. Once you do so, you cannot do it again until you take a short or long rest. 

You can learn this modification multiple times, and for each time you learn it beyond the first, you have one additional use of this ability. The penalty to your misfire increases by 1 each time you learn this modification beyond the first.

Laser Sight

Requirements: 15th level, +2 to misfire score

Once per round, you can reroll an attack roll that missed. Additionally, you can make an opportunity attack when a creature moves more than 15 feet within your guns range.

Blood Siphon

Requirements: 15th level, +1 to misfire score

You attach a tube to the underside of your gun that can siphon your blood to generate bullets. When your gun is out of bullets, you can generate another bullet as a free action. You choose to lose a number of hit points up to a maximum of 20, and when you hit with an attack roll using one of these bullets, you deal necrotic damage equal to the amount of hit points spent to generate the bullet instead of the weapons normal damage. You cannot heal the damage done to yourself this way until the start of your next turn.

You can modify the sights on your weapon to better allow you to see and hit targets in different situations.

Night Vision Scope

Requirements: 1st Level, firearm must have the two handed property

While aiming through the scope of your firearm, you have darkvision out to a range of 40 feet.

Simple Scope

Requirements: 1st level

You put a simple scope on your weapon, giving yourself advantage on perception checks that rely on sight if you look through the scope of your gun.

Gun Shield

Requirements: 5th Level, firearm must have the two handed or heavy property,+1 to misfire score

You add a shield on top of your gun, granting you +2 AC until the start of your next turn after making an attack with it.

Telescopic Sight

Requirements: 9th Level, +1 to misfire score

You no longer have disadvantage for shooting within your firearms far range.

Marksman Scope

Requirements: 9th Level, +2 to misfire score

Your crit range increases by 1, you gain a +1 to attack rolls, but you have disadvantage to hit targets within 30 feet of you.

Thermal Scope

Requirements: 11th Level, +1 to misfire score

You get blindsight out to 60 feet while looking through your scope. With this blindsight, you can only see creatures that emit body heat.

High Noon

Requirements: 15th Level, +2 to misfire score

As a reaction, you can use an auto targeting system. You make one attack and damage roll against all creatures (maximum number of creatures equal to your proficiency bonus) that you can see within your firearms range with advantage, regardless of how many bullets are left in your gun. You cannot critically hit or misfire with with this attack. Once you use the auto targeting system, you cannot use it again until you finish a short or long rest.

You can modify your guns receiver, allowing for your gun to let loose more powerful shots, or to automatically load bullets for you.

Collapsible

Requirements: 1st Level, firearm must not have the heavy property

This gun is capable of looking like a normal everyday object, or it can collapse to become really small to stealthily transport it. If suspicion arises, the target must succeed on a perception or investigation check (DM decides which is applicable) vs your save DC to recognize it as a weapon.

Kinetic Receiver

Requirements: 1st Level

You install an autoloading mechanism that is activated by swinging it around. Whenever you take the dash or disengage action, your weapon reloads itself.

Elemental Shot

Requirements: 5th Level, +1 to misfire score

Choose a cantrip: Firebolt or Ray of Frost. You can cast this cantrip as a bonus action after you take the attack action with your firearm. You make an attack roll with your weapon for the cantrip. You can use this a number of times equal to your wisdom modifier before you must take a short or long rest.

Critical Reload

Requirements: 5th Level, +2 to misfire score

Whenever you score a critical hit, a bullet returns to the mag of your gun. Additionally, your crit range is expanded by 1.

Forceful Shots

Requirements: 9th Level, +1 to misfire score

Once per turn, you can move a target 5 feet after being shot. If they fail a strength save equal to your save DC, they are also knocked prone.

Auto Loading Holster

Requirements: 9th Level, +1 to misfire score

If you make an attack with a different weapon, the firearm with this modification is reloaded. This can only be used once per round.

Elemental Receiver

Requirements: 11th Level, +1 to misfire score

You can change your gun's base damage type to either acid, cold, fire, or lightning damage. Once per round, your gun deals an extra 1d6 of the chosen damage type. You can learn this modification multiple times, and each time you do, you must select a different damage type. You decide the damage type before you make each attack. Your misfire score does not stack as a result of taking this modification multiple times.

Hawkmoon

Requirements: 11th Level, +1 to misfire score

One shot in the mag has a chance of doing +5 damage. Each time you shoot with this weapon you roll 1d6, and if the number is a 6, that shot deals the extra damage. Once you have rolled a 6, even if the attack missed, this modification is disabled until you reload your gun. +1 misfire score.

You can learn this modification one additional time, which allows you to roll a second 1d6 whenever you shoot the firearm. If either of the dice roll a 6, you deal +5 damage. Every time you roll a 6 on either of the dice, even if you miss, you roll 1 less d6 until you reload your gun. If both the dice roll a 6 on the same attack, it deals +10 damage, and even if the attack missed, this modification is disabled until you reload your gun. You also have an additional +1 to misfire score for learning the modification again.

Legendary Receiver 

Requirements: 15th Level, +1 to misfire score

You can change your gun's base damage type to radiant or necrotic. Once per round, your gun deals an extra 1d6 of the chosen damage type. You can learn this modification multiple times, and each time you do, you must select a different damage type. You decide the damage type before you make each attack. Your misfire score does not stack as a result of taking this modification multiple times. This modification can be put on your gun alongside the Elemental Receiver modification, and if Elemental Receiver is already on your gun, then Legendary Receiver does not add +1 to your misfire score.

Celestial Receiver

Requirements: 15th Level, +1 to misfire score

Whenever you score a critical hit, you or an ally within 15 feet of you regenerate a number of hit points equal to your wisdom modifier.

You can modify your guns magazine to either hold more bullets, or to be able to take a special kinds of bullet. 

Rubber Bullets

Requirements: 1st Level

Your firearm deals bludgeoning damage, and can make nonlethal attacks.

Extravagant Bullets

Requirements: 1st Level

You can cause a non harmful small explosion of sparks or a stream of colorful fire to come from your gun's barrel, giving you advantage on performance checks that involve using this firearm.

Ammo Capacity

Requirements: 5th Level, firearm must not have the light property

You add +1 to your reload score. You can learn this modification as many times as you want, and for each time you have learned this modification beyond the first, the bonus increases by 1.

Incendiary Rounds

Requirements: 5th Level, +1 to misfire score for the shot

As a bonus action, you can load an incendiary round into your gun. Your next attack with that firearm deals fire damage instead of it's normal damage, and all creatures within 5 feet of the target you hit takes fire damage equal to your wisdom modifier.

Armor Piercing Rounds

Requirements: 9th Level, firearm must not have the light property, +1 to misfire score for the shot

As a bonus action, you can load an armor piercing round into your gun. If there is another target directly behind your original target within a 30 foot long straight line, they are subjected to the same attack and damage roll.

Healing Bullets

Requirements: 9th Level

As a bonus action, you can load a healing bullet into your gun. You can use an attack to shoot an ally or yourself to heal instead of damage. The healing is equal to 3d4+ your wisdom modifier. You have two of these bullets, and you get them back after a long rest. You can learn this modification as many times as you want, and for each time you have learned this modification beyond the first, you get one additional healing bullet before you must take a rest.

Hollow Point Rounds

Requirements: 11th Level, +2 to misfire score

You now use a more lethal type of bullet in your firearm. You can add your wisdom modifier to damage rolls.

Bouncing Bullet

Requirements: 11th Level, +1 to misfire score for the shot

As an action, you can load a ricocheting bullet into your gun and shoot it. You pick an area within your guns range, and the the bullet bounces, hitting all targets within 30 feet of the chosen area, regardless of cover assuming the bullet has some way of physically getting there. You use the same attack and damage roll for all targets, and can hit up to a number of targets equal to your proficiency bonus.

Key Point Rounds

Requirements: 15th Level, +3 to misfire score

You now use the most deadly type of bullet in your firearm. Whenever you score a critical hit, the target suffers additional damage equal to half your level. +3 to misfire score

Ethereal Bullets

Requirements: 15th Level, +1 to misfire score

When you load your gun, you can choose to load your ethereal bullets. Your bullets deal force damage, and ignore all cover, including full cover, if you are within 30 feet of the object giving cover. You can also allow your bullets to pass through any creatures of your choice without harming them while they are within your normal range.

At 20th level, you learn one of the following modifications

Masterwork

Your guns gets a +1 to hit, +1 to damage, and it's crit range increases by 1.

Emergency Reload

When your gun is depleted of ammo, it immediately fully refills itself

Lightning Strike

As a bonus action, you can load a special round attached to a conductive string. On a hit, you press a button that shoots electricity along the conductive string. You cast chain lightning on the target. On a miss, you retract the bullet back into your gun. Once you use the ability and hit with it, you cannot do so again until you finish a short or long rest.

Expert Modifier

You pick one modification category. You can have two modifications from that category on the same gun. If you are the Inventor subclass, this increases to three. You can change the chosen category on a short or long rest.