Firearm Modifications · Runarcana RPG

Upgrading Firearms

Marksmen and Techmaturges are not just firearm users. Their knowledge and practice let them push a firearm beyond what it was built to do. With gunsmith’s tools, material components, and time, they can upgrade their weapons.

Characters of other classes can also do this, but they need proficiency with the Gunsmith Craft.

Upgrade Capacity. By spending 1 hour of work and 50 GP in materials, you can increase the maximum capacity of some firearms using your gunsmith’s tools. Doing so increases the weapon’s Capacity by +1, up to the maximum for that weapon type. For each hour of work, you must make a Technology check DC 20; if you don’t have proficiency with the Gunsmith Craft, this check is made with disadvantage.

On a success, your work continues normally. On a failure, the weapon’s Capacity and Misfire both increase by +1. You can spend half an hour of work and 25 GP in materials to repeat the check, removing the Misfire increase on a success.

Capacity Limit

Handcannon, Axe Cannon: 2
Light Bayonet, Derringer: 5
Flintlock Pistol, Carbine, Shotgun, Musket, Sword Musket: 6

Upgrade Damage. By spending 2 hours of work and 100 GP in materials, you can modify a firearm to deal more damage using your gunsmith’s tools. Doing so requires a Technology check DC 25; if you don’t have proficiency with the Gunsmith Craft, this check is made with disadvantage.

On a success, the weapon gains its new damage according to its type. On a failure, the weapon’s damage doesn’t change and it gains +1 Misfire and +2 Strength. You can spend another hour of work and 25 GP in materials to make a new roll, removing the added Misfire and Strength on a success.

Weapon Damage
Carbine, Handcannon, Flintlock Pistol, Light Bayonet, Derringer: 1d8
Shotgun, Revolver: 2d6
Pistol: 2d8

Firearm and Ammunition Modifications

Some classes that use firearms can modify these weapons and their ammunition, adapting them to their adventures and often making them even deadlier.

Below are the tables for Firearm and Ammunition modifications, separated by the tier of each modification.

The rules for these modifications are detailed in the classes that have this resource.

Weapon Modifications

Modifications
Tier	Modification	Effect	Type	Weapons
1	Rifled Barrel	Your weapon's barrel has grooves that help guide the ammunition, increasing shot accuracy. Its misfire threshold and critical range are both reduced by 1.	Barrel	All
1	Exhaust Barrel	The weapon vents its gases more efficiently, lowering the required Strength value and the Misfire threshold by 1.	Barrel	All
1	Coupled Blade	Modifies a Medium or Long ranged weapon. Adding a mount for a small blade with a dagger, that dagger keeps its standard properties, and the modified weapon gains the mutable property.	Extra	Medium, Long
1	Light Alloy	The weapon becomes lighter, lowering the required Strength value by 2.	Alloy	All
1	Nonporous Alloy	Neither the weapon nor its loaded ammunition are affected by moisture or submersion. You can use the weapon to make attacks underwater normally, up to the weapon's normal range.	Alloy	All
1	Silencing Alloy	This weapon gains the Silenced property.	Alloy	Light, Medium, Long
1	Hardening Rune	While this weapon is within 200 feet of you, it no longer needs maintenance to function normally.	Personal	All
1	Memory Drum	When you hit a target with a critical attack, the weapon used is automatically reloaded. This happens a number of times equal to your Wisdom modifier per short or long rest.	Reload	All
2	Vampiric Weapon	When making an Attack on your turn, you can choose to suffer 1 point of damage (which cannot be mitigated) to fire a shot beyond your weapon's capacity using spectral ammunition; you can do this up to 2 times. Your current and maximum hit points are reduced until the end of your next long rest. If your maximum hit points are reduced to 0, you die instantly.	Reload	All
2	Auto-Reload	When this weapon's ammunition reaches 0, it fully reloads. This happens a number of times equal to your Wisdom modifier per short or long rest and expends ammunition normally.	Reload	All
2	Short Barrel	The weapon can only make attacks at its normal range. When it hits a target that is up to 1 size category larger than you, that target is pushed 10 feet back.	Barrel	Medium, Long
2	Minor Elemental Barrel	The damage dealt by the weapon becomes acid, lightning, cold, or fire. You choose the damage type when making the modification.	Barrel	All
2	Long Barrel	The weapon can attack up to its maximum range without disadvantage from distance or hostile weather.	Barrel	Light, Medium, Long
2	Interchangeable	This weapon has a mechanism that makes swapping its barrel easier. You can swap the weapon's barrel using a bonus action.	Extra	Light, Medium and Long
2	Thermal Alloy	This weapon's temperature is not increased or decreased by magical effects such as the heat metal spell, and it is immune to freezing.	Alloy	All
2	Action Drum	A small apparatus for heated moments that allows you to use an Attack action to reload the weapon.	Reload	Light, Medium, Long
2	Old Faithful	The weapon's Misfire threshold is reduced by 2.	Personal	All
3	Pressurized Barrel	The weapon deals 1 additional damage category, but the required Strength value increases by 1.	Barrel	All
3	Ethereal Alloy	Shots fired by this weapon hit incorporeal creatures as though they were corporeal, and attacks made with this weapon deal an additional 1d4 energy damage.	Alloy	All
3	Tactical Scope	Using a bonus action, you can aim through the scope to gain advantage on your next attack roll with this weapon.	Personal	All
3	Vampiric Reload	When you reduce an opponent's hit points to 0, or roll a natural 20, your weapon is completely reloaded with spectral ammunition. Spectral ammunition cannot be removed from the weapon, only fired.	Reload	All
3	Taser	This weapon is fitted with a mechanism that builds up a charge with every shot, capable of delivering electrical discharges on touch. With an action, you can touch a creature, forcing it to make a Dexterity saving throw DC equal to your Trick Shot DC. On a failure, it takes 1d12 lightning damage and is Incapacitated until the start of your next turn. The weapon can store 1 charge and gains a charge for every three shots fired.	Extra	All
4	Modular Design	You can modify this weapon during a short rest.	Personal	All
4	Major Elemental Barrel	The damage dealt by the weapon becomes antimonic, plasma, glacial, or incinerating. You choose the damage type when making the modification.	Barrel	All
4	Taser Blade	This weapon is fitted with a mechanism that builds up a charge with every blow, capable of delivering electrical discharges on touch. On a successful melee attack, the creature takes an additional 2d8 lightning damage and must make a Constitution saving throw DC equal to your Trick Shot DC. On a failure, the target is Incapacitated until the start of your next turn. The weapon can store 1 charge and gains a charge for every three attacks made.	Extra	Bayonet
4	Kinetic Alloy	The weapon's critical range is reduced by 1.	Alloy	All
4	Duplicator Drum	Ammunition loaded in this drum can be fired twice. After the first time it is fired, a spectral trace of it remains ready to be fired.	Reload	All

Ammunition Modifications

Modified Ammunition
Tier	Modification	Price	Weapons	Effect
1	Snare	3 GP	Medium, Long and Cannons	This ammunition deals no damage, but when an enemy is hit by it, they become Restrained. Medium or smaller creatures are Restrained for 3 rounds, Large creatures for 2, Huge creatures for 1, and Gargantuan creatures are unaffected. Creatures affected by this ammunition can make a Strength saving throw DC equal to your Trick Shot DC at the end of each of their turns to end this condition.
1	Corrosive Ammunition	2 GP	All	Successful attacks made with this weapon deal an additional 1d4 acid damage.
1	Ricochet Ammunition	1 GP	Light, Medium and Long	Attacks made with this weapon can ricochet. If an attack hits, you can choose an additional target within 10 feet of the original target and make an attack roll with disadvantage against that second target. The ricochet deals 1d6 + your Dexterity modifier piercing damage. This second attack is not affected by the weapon's Misfire threshold.
1	Piercing Ammunition	2 GP	Light, Medium and Long	Attacks made with this ammunition ignore resistance to piercing damage.
2	Restorative Charge	5 GP	Light, Medium and Long	When a creature is hit by this ammunition, it takes no damage and instead regains 1d10 + 5 times your proficiency bonus in hit points. A forewarned ally can voluntarily be targeted by this, treating their AC as 10.
2	Explosive Dart	7 GP	Light, Medium and Long	When this ammunition hits a target, it explodes, forcing all creatures within a 5-foot radius of the target to make a Dexterity saving throw DC equal to your Trick Shot DC. On a failure, an affected creature takes 4d6 fire damage and, if it is Large or smaller, falls Prone.
3	Expansive	10 GP	All	When this ammunition hits a target, the round expands, causing the hit target to take Bleeding equal to half your proficiency bonus.
3	Incendiary	10 GP	All	When this ammunition hits a target, it explodes, causing the hit target to become Scorched, taking your proficiency bonus as fire damage until it is put out.
4	Fragmentation	50 GP	Light, Medium and Long	When this ammunition hits a target, it explodes into several fragments inside the target's body, causing the hit target to take half your proficiency bonus in disruptive damage every turn it moves. Removing these fragments requires surgery, made with a Medicine check DC 20 or the regenerate spell. This ammunition has no effect on undead, constructs, creatures without blood circulation, and creatures above Large size.
4	Paralyzing	50 GP	All	A creature hit by this ammunition must make a Constitution saving throw DC 10 + your proficiency bonus + your Wisdom modifier (or Intelligence, when fired by a Techmaturge). On a failure, the creature is Paralyzed for 3 rounds. The creature can repeat the saving throw at the start of each of its turns to end this condition.