Got super enthusiastic about the gunslinger subclass and went off the wall with weapons mods, lore, and a homebrew gunslinger monster. Every single item is fully fleshed out for DDB including tooltips, item weight, descriptions, and formatted to look like official material. It is made exclusively for Matt Mercer's firearm rules, not the ones found in the monster manual.
Almost everything you need is in the Weapon's Mod Compendium which is a scroll you can give your players so that they can keep track of what the mods are and how to use them. The scroll explains what all the mods are, what can be attached to what weapons, and how to do that. I will post the text of this at the bottom of this post. All the links will take you to the homebrew item so you can add it to your game.
Gunslinger's Oath a legendary scroll I made for my campaign, gives some hints to the background of guns in my world and immediately provides some story hooks. Might not fit your game just wanted to add it
Gunslinger Monsterbased on the drow gunslinger and updated with some gunslinger subclass features. Fully ready for encounters.
And lastly, DDB has an amazing way to keep track of this now by using containers. Here are the steps I used to fully kit out my playtest character
Add a container to your character
Make the weight overwrite 0
Rename it to the name of the weapon
Add the weapon and any mods into that container
Now you can keep track of exactly what weapon has what mod. This works so perfectly and makes this complex system super easy to keep track of. Also, consider adding custom notes to the notes field to make sure you have everything accounted for.
For help with the bonus action attacks consider adding the fighting initiate feat with the two-weapon fighting style for free. This will simply help you to keep track of your palm pistols that you fire with a bonus action. You can click the dual wield option on your palm pistols and then they will be separated into the bonus actions section and still add your dex mod to the attacks. Obviously, this is for ease of use so remember that you don't actually have the feat if you start dual-wielding melee weapons...(but why would you with these awesome mods!)
Here is the Weapon's Mod Compendium! would love to hear any feedback as I've only playtested this by myself, my biggest concern is the cost of the mods. I want it to be expansive enough that it will take a long time to have a full arsenal but also accessible enough to get started right away. I think I have that now but I'm not sure.
We have traveled far and wide to assemble this list of all known gunslinger mods. This technology has the power to change our society forever, make sure it doesn't fall into the wrong hands...
Assembling a weapons mod
Each firearm can accept one of each type of weapons mod unless stated by the mod itself. You can craft a weapons mod and attach it to a firearm by spending 30 minutes with your Tinker’s Tools and expending an amount of resources equal to the mods cost (typically metal).
This barrel mod can hold items roughly smaller than a clenched fist, such as a ring, grappling hook, or stone. The barrel does not protect the items from any damage they may receive from being fired through the gun.
Barrel Attachment Mods - cannot be attached to a blunderbuss
This barrel attachment mod has been enchanted with the silence spell. It creates a 3ft by 1ft cylinder of silence around it. The Arcane silencer does not remove a spellcaster's ability to cast spells.
This under-barrel mod fires projectiles with the same loudness as a bow and arrow and can be fired underwater. Ranged attacks made with this weapon have a 30ft penalty to their normal range. In addition, it does not damage the ammunition it fires. Your firearms reload is changed to 1
This under-barrel mod attaches to a firearm with the light property. While attached you can use the firearm as a bonus action, and take opportunity attacks with it.
This sentient sight mod shares your vision but cannot suffer from the blinded condition or an effect that causes the blinded condition. If an enemy is concealed by an effect such as smoke or the darkness spell, it can still see them out to a range of 60ft. An enemy concealed by a wall or other hard surface cannot be seen by the A.G.S. When you make an attack roll with a firearm while this mod is attached to it, you can rely on the A.G.S. to direct your aim. When you do so it guides you to the physically closest enemy it can see. You cannot suffer disadvantage from an effect that obstructs your vision when using the A.G.S. to target a foe. The A.G.S. cannot sense an invisible creature. Requires Attunement
This sight mod attaches to the rear of a firearm. When peering through this sight You gain darkvision out to a range of 90ft. If you already have darkvision from your race, its range increases by 30ft while using the scope. Using this scope in bright light causes you to suffer from the blinded condition.
This sight mod attaches to a firearm with the two-handed property. It increases the firearms normal range by 120ft. When using the scope you suffer disadvantage against targets within 30 ft of you.
Specialty Mods - can attach one of each
Elemental ammo (40gp)
This specialty mod deals Acid, Cold, Fire, Lightning, or Poison damage (you choose when crafting it) when fired from a firearm.
This specialty mod is inserted into the breech of a firearm. When the weapon misfires the rebounder safely ejects the spent materials and the weapon doesn't misfire. The rebounder is destroyed in the process.
This specialty mod attaches to the rear of a firearm. While attached it can hold two separate sight mods. As a bonus action, you can swap one sight mod for another or remove both sights from your firearm.
This specialty mod can be loaded with a light firearm attaching it to your forearm or wrist. While the firearm is loaded you can draw or stow it as a free action. The firearm is concealed if covered by clothing requiring a successful investigation check (DC 15) to discover.
Got super enthusiastic about the gunslinger subclass and went off the wall with weapons mods, lore, and a homebrew gunslinger monster. Every single item is fully fleshed out for DDB including tooltips, item weight, descriptions, and formatted to look like official material. It is made exclusively for Matt Mercer's firearm rules, not the ones found in the monster manual.
Almost everything you need is in the Weapon's Mod Compendium which is a scroll you can give your players so that they can keep track of what the mods are and how to use them. The scroll explains what all the mods are, what can be attached to what weapons, and how to do that. I will post the text of this at the bottom of this post. All the links will take you to the homebrew item so you can add it to your game.
Two other items not in the Weapon's Mod Compendium
Gunslinger's Oath a legendary scroll I made for my campaign, gives some hints to the background of guns in my world and immediately provides some story hooks. Might not fit your game just wanted to add it
Gunslinger Monster based on the drow gunslinger and updated with some gunslinger subclass features. Fully ready for encounters.
And lastly, DDB has an amazing way to keep track of this now by using containers. Here are the steps I used to fully kit out my playtest character
Now you can keep track of exactly what weapon has what mod. This works so perfectly and makes this complex system super easy to keep track of. Also, consider adding custom notes to the notes field to make sure you have everything accounted for.
For help with the bonus action attacks consider adding the fighting initiate feat with the two-weapon fighting style for free. This will simply help you to keep track of your palm pistols that you fire with a bonus action. You can click the dual wield option on your palm pistols and then they will be separated into the bonus actions section and still add your dex mod to the attacks. Obviously, this is for ease of use so remember that you don't actually have the feat if you start dual-wielding melee weapons...(but why would you with these awesome mods!)
Here is the Weapon's Mod Compendium! would love to hear any feedback as I've only playtested this by myself, my biggest concern is the cost of the mods. I want it to be expansive enough that it will take a long time to have a full arsenal but also accessible enough to get started right away. I think I have that now but I'm not sure.
We have traveled far and wide to assemble this list of all known gunslinger mods. This technology has the power to change our society forever, make sure it doesn't fall into the wrong hands...
Assembling a weapons mod
Each firearm can accept one of each type of weapons mod unless stated by the mod itself. You can craft a weapons mod and attach it to a firearm by spending 30 minutes with your Tinker’s Tools and expending an amount of resources equal to the mods cost (typically metal).
Barrel Mods
Double Barrel (100gp)
This barrel mod replaces your existing barrel. Your weapon reload is changed to 2 and your misfire is increased by 1.
Rifled Barrel (25gp)
This barrel mod increases the firearms normal range by 30 ft.
Utility Barrel (50gp)
This barrel mod can hold items roughly smaller than a clenched fist, such as a ring, grappling hook, or stone. The barrel does not protect the items from any damage they may receive from being fired through the gun.
Barrel Attachment Mods - cannot be attached to a blunderbuss
Arcane Silencer (500gp)
This barrel attachment mod has been enchanted with the silence spell. It creates a 3ft by 1ft cylinder of silence around it. The Arcane silencer does not remove a spellcaster's ability to cast spells.
Bayonet (10gp or a shortsword)
This melee weapon attaches to a firearm that does not have the light property allowing you to make melee attacks and opportunity attacks with it.
Small Bayonet (2gp or a dagger)
This melee weapon attaches to a firearm allowing you to make melee attacks and opportunity attacks with it.
Under-Barrel Mods
Air Propulsion System (A.P.S.) (150gp)
This under-barrel mod fires projectiles with the same loudness as a bow and arrow and can be fired underwater. Ranged attacks made with this weapon have a 30ft penalty to their normal range. In addition, it does not damage the ammunition it fires. Your firearms reload is changed to 1
Auto-Loader (150gp)
This under-barrel mod adds 1 to the reload of a firearm. To do so you must expend your reaction after you have made an attack with a firearm.
Barrel Blade (25gp or a Rapier or Longsword)
This under-barrel mod attaches to a two-handed firearm allowing you to make melee and opportunity attacks with it.
Hair Trigger (50gp)
This under-barrel mod attaches to a firearm with the light property. While attached you can use the firearm as a bonus action, and take opportunity attacks with it.
Sight Mods - cannot be attached to a blunderbuss
Arcane Guidance System (A.G.S.) (600gp)
This sentient sight mod shares your vision but cannot suffer from the blinded condition or an effect that causes the blinded condition. If an enemy is concealed by an effect such as smoke or the darkness spell, it can still see them out to a range of 60ft. An enemy concealed by a wall or other hard surface cannot be seen by the A.G.S. When you make an attack roll with a firearm while this mod is attached to it, you can rely on the A.G.S. to direct your aim. When you do so it guides you to the physically closest enemy it can see. You cannot suffer disadvantage from an effect that obstructs your vision when using the A.G.S. to target a foe. The A.G.S. cannot sense an invisible creature. Requires Attunement
Darkvision Scope (500gp)
This sight mod attaches to the rear of a firearm. When peering through this sight You gain darkvision out to a range of 90ft. If you already have darkvision from your race, its range increases by 30ft while using the scope. Using this scope in bright light causes you to suffer from the blinded condition.
Iron Sight (50gp)
This barrel mod increases the firearms normal range by 30ft.
Marksman's Scope (250gp)
Specialty Mods - can attach one of each
Elemental ammo (40gp)
This specialty mod deals Acid, Cold, Fire, Lightning, or Poison damage (you choose when crafting it) when fired from a firearm.
Rebounder (75gp)
This specialty mod is inserted into the breech of a firearm. When the weapon misfires the rebounder safely ejects the spent materials and the weapon doesn't misfire. The rebounder is destroyed in the process.
Sight Mod Switcher (S.M.S.) (350gp)
This specialty mod attaches to the rear of a firearm. While attached it can hold two separate sight mods. As a bonus action, you can swap one sight mod for another or remove both sights from your firearm.
Spring Loaded Arm Mount (S.L.A.M.) (100gp)
This specialty mod can be loaded with a light firearm attaching it to your forearm or wrist. While the firearm is loaded you can draw or stow it as a free action. The firearm is concealed if covered by clothing requiring a successful investigation check (DC 15) to discover.
Elemental Ammo (Acid, box of 20)
Elemental Ammo (Cold, box of 20)
Elemental Ammo (Fire, box of 20)
Elemental Ammo (Lightning, box of 20)
Elemental Ammo (Poison, box of 20)
I was looking for something like this! Thank you!