Firearm Modifications
To add a modification to an item you own, you must first purchase it. The Cost of a modification is often contingent on the specific item it is intended to modify or other factors.
Then, you must spend a small amount of time applying the modification. This counts as light activity for the purposes of resting. At the end of the time period, you must make a skill check using Mechanical tools to determine your success at applying the modification. On a success, the modification is applied successfully. On a failure, the modification is not applied to the item. On a critical failure, the modification is damaged beyond repair. You can decide to spend additional care and time applying a modification. If you spend a number of hours applying a modification, you gain a bonus to the skill check equal to the number of hours multiplied by 2, up to a maximum of +10.
Removing an applied modification is done in the same manner to applying a modification, but the DC for the check is reduced by 5. On a success, the modification is removed successfully. On a failure, the modification is not successfully removed from the item. On a critical failure, the modification is damaged beyond repair.
Modifications usually have restrictions placed on them that limit the types of items the modification can be applied to. Firearms can only have one the same modification applied at any one time, unless otherwise specified.
Firearm Modifications
| Modification | Cost | Check DC | Extra Weight |
|---|---|---|---|
| Auto Mechanism | 275 gp | 16 | 0 lbs. |
| Bayonet Weapon | Variable | 16 | Variable |
| Box/Cylinder Conversion | 275 gp | 14 | 0 lbs. |
| Carbine Extension | 275 gp | 16 | 2 lbs. |
| Extended Barrel | 150 gp | 14 | Variable |
| Expanded Magazine | 500 gp | 14 | 0 lbs. |
| Integrated Shield | 275 gp | 12 | 1 lbs. |
| Shortened | 150 gp | 14 | -2 lbs. |
Auto Mechanism
The firearm gains the Burst Fire property (DMG, pg. 267).
Restrictions. Firearm must have the Expanded Magazine modification.
Bayonet Weapon
Choose a light one-handed melee weapon. The chosen weapon is integrated into the firearm and is usable as long as the firearm is being used. The weight of the firearm is increased by half the weight of the alternate weapon. This kit includes the weapon to be installed, which cannot be used in its uninstalled form.
Cost. Cost of bayonet weapon x2
Box/Cylinder Conversion
You develop self contained cartridges for your firearm that allows it to load from either a spring loaded box magazine (if it is a musket) or a rotating cylinder (if it is a pistol). The firearm loses the Loading property and gains the Reload (5 shots) property (DMG, pg. 267).
Carbine Extension
By adding a stock and foregrip to a one-handed firearm you can significantly reduce its recoil. The weapon gains the Foregrip (+10/+30) property.
Restrictions. Firearm must not have the Two-handed property.
Extended Barrel
The weapon's weight is increased by 1/4th (minimum 1 lb.). The normal range of the weapon is increased by one step on the following chart. The long range of your weapon is three times its new normal range.
| 30 ft. | 40 ft. | 50 ft. | 60 ft. | 80 ft. | 100 ft. | 120 ft. | 150 ft. |
Restrictions. Firearm must not have the Shortened modification.
Expanded Magazine
The firearm is modified to take much larger magazines. It's Reload property increase to Reload (10 shots) .
Restrictions. Firearm must be a musket with the Box/Cylinder Conversion modification.
Integrated Shield
While wielding this weapon, you are also treated as though you were wielding a Buckler.
Restrictions. Two-handed firearms only, weapon must not have the Alternate Weapon modification.
Lightweight
The firearm's weight is reduced by 3 lbs. (to a minimum of half the firearm's original weight).
If the firearm is a pistol and lacks the Foregrip and Light properties, then it gains the Light property.
Shortened
The weapon's weight is reduced by 1/4th (to a minimum of half the weapon's original weight). The normal range of the weapon is reduced by one step on the following chart. The long range of your weapon is three times its new normal range.
| 30 ft. | 40 ft. | 50 ft. | 60 ft. | 80 ft. | 100 ft. | 120 ft. | 150 ft. |
If the weapon is a pistol and lacks the Foregrip and Covert properties, then it gains the Covert property.
Restrictions. Firearms only, weapon must not have the Extended Barrel modification.
Accessories
Accessories function similarly to modifications, in that they provide some modification to the except they can be applied quickly and without a skill check. Applying a modification to an item is an action.
Weapon Accessories
| Items | Cost | Weight |
|---|---|---|
| Scope | ||
| x2 | 150 gp | 1/2 lb. |
| x4 | 275 gp | 1 lb. |
| x8 | 500 gp | 1 lb. |
| Suppressor | 55 gp | 1/2 lb. |
Scope. Scopes are used to increase the range of a weapon, allowing the user to shoot more consistently at longer distances farther. By spending a bonus action to line up a shot with your scope, you increase the normal and long ranges of the weapon by an amount shown in the following table until the start of your next turn.
| Scope | Normal Range Increase | Long Range Increase |
|---|---|---|
| x2 | x1.5 | x1.0 |
| x4 | x2.0 | x1.5 |
| x8 | x3.0 | x2.0 |
Suppressor. A suppressor is a device attached to the barrel of a firearm which reduces (but don't negate) the amount of noise and visible muzzle flash generated by firing. When you make a ranged attack with a suppressed firearm, creatures further than 30 feet from you don't hear the gunshot.
New Properties
Covert. You have advantage on Dexterity (Sleight on Hands) checks to conceal this weapon.
Foregrip. This weapon can be used with one or two hands. If used in two hands, its normal and long ranges are increased by the values in brackets. If no values are given, then the ranges are doubled.
Special Ammunition
Specialised ammunition can be bought which alters the behavior of the firearm it is used for. When buying special ammunition, you purchase the ammunition the cost listed, which is given for 10 bullets.
Most ammunition cannot have more than one property of the same type, such as multiple cores or multiple playloads, but you can combine any Payload with any Core. This combines the cost of the two special properties into one. For example, armor piercing explosive bullets would cost 40 gp per 10 bullets.
Hollow point. This weapon deals an extra 1d4 points of damage against unarmored targets.
Armour Piercing. The firearm's attacks ignore resistance to Piercing damage from non-magical weapons.
Explosive. Designed to produce a small explosion on impact, successful attacks using explosive ammunition deals an additional 1d6 bludgeoning damage.
Holy Water. These bullets, a favourite of demon slayers, release holy water on impact. Successful attacks using holy water ammunition deals an additional 1d6 radiant damage if the target is a fiend or undead.
Incendiary. Igniting briefly on impact, successful attacks using incendiary ammunition deals an additional 1d4 fire damage.
High-explosive incendiary. High-explosive incendiary ammunition combines the effects of explosive and incendiary ammunition.
Silvered. Silvered ammunition follows the same rules detailed in chapter 5 of the Player's Handbook.
Special Ammunition
| Ammunition | Type | Cost |
|---|---|---|
| Hollow Point | Payload, Core | 20 gp |
| Armour Piercing | Core | 20 gp |
| Explosive | Payload | 20 gp |
| Holy Water | Payload | 10 gp |
| Incendiary | Payload | 15 gp |
| High-explosive incendiary | Payload | 55 gp |
| Silvered | Coating | See PHB |