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Black Powder Wizard: D&D Firearm Rules

There are firearms in the world I run games in. This post contains a brief description of how they work, assuming D&D 3.5 or Pathfinder rules are being used.


Range Increment: Weapons are accurate up to their range increment, with each increment beyond that imposing a -2 penalty. Firearms can shoot up to five times their range increment.

Exploding Dice: Firearms are very lethal. If you’re hit, it’s most likely that you’ll take a helluva lot of damage. Every time the max number is rolled on a damage die, add another die of damage. Example: If damage is 1d6, and you roll a 6, roll another d6. If you roll a 6 on that one, roll another, and so forth, until you stop rolling sixes.

Misfire: The Misfire chance is a range of numbers, starting at 1 and going up. If an attack roll with a firearm falls within its misfire range–before attack bonuses and penalties are applied–then the weapon misfires. Roll on the following table to determine what happens. Roll a d8 if it is a small gun–a pistol or a musket–and roll 1d10 if it’s a large gun–a cannon, or an experimental gatling gun or some such thing.

Misfire Table

1. Partial misfire. The main charge is still intact, and the gun can be reloaded with a minor action (just priming needed)
2. Total misfire. The gun does not go off, nothing else happens. Gun must be reloaded again.
3. Smoky misfire. The gun does not go off, and the player takes a -2 penalty to attacks on the next turn because the smoke burns their eyes.
4. Loud misfire. The sound of the misfire dazes the player, and they lose an action.
5. Fouled barrel. The player must spend 1d4 rounds clearing the blockage before the weapon can be fired again.
6. Hang-fire. It takes longer than usual for the main powder charge to ignite. If the person firing the gun is a trained user (has the Firearms proficiency) then they can make a concentration check to keep the gun on target: this check will be treated as a second attack roll, except using the characters concentration skill instead of attack bonus. Doing so, however, will lose the shooter their dexterity bonus to armor until their next turn. If the concentration/attack hits, then congratulations, roll damage. If it rolls within the misfire range a second time, you have inadvertently hit either yourself or an ally. If the character does not have the Firearms feat, they can still make the concentration roll, but at -4.
7. Damaging misfire. The gun is damaged and requires repairs equivalent to small gun 1d4x10, heavy gun 1d6x10, very heavy gun 2d8x10. If the gun is a longarm, it may be cheaper to cut the barrel down to pistol size (repairs cost / 2 or DC 18 Craft check).
8. Explosion. The gun is destroyed, and the wielder take damage as though they were fired upon by that weapon.
9. Damage Person: Roll to determine what body part is ruined by the explosion.
10. Large explosion. The wielder and anyone around them take damage as though they were fired upon by that weapon. Reflex save for half for everyone but the wielder.

Reloading: An untrained user with a powder horn and a pouch of balls can load a pistol in three rounds, a musket in four. Using paper cartridges (the bullet and the powder needed to fire it are loaded into a small paper pouch, which is used to prime the flash pan and fire the gun) reduces that to two rounds for a pistol and three for a musket. Having the Weapon Proficiency: Firearms feat reduces that by another round.


Weapon Proficiency: Firearms: Decreases the time needed to reload a firearm by one round. In systems that use feats, firing guns without this feat gives the usual -4 penalty for not knowing how to aim.

Sniper’s Perfection: When using black-powder weapons, the best way to increase accuracy is to make your own bullets using your own finely-tuned molds. You take time and care to make near-perfect bullets for your guns, giving you a +2 accuracy bonus with any ammunition you have made yourself. Prerequisite: Weapon Proficiency: Firearms, Craft: Firearms.

Firearms Drill: Decreases the time needed to reload a firearm by an additional round. If this would decrease the load time to zero rounds, it reduces it to a standard action instead. A character with this feat may choose to reduce the load time by an additional round (or to move action, if it was a standard action), at the cost of -4 to the attack roll and +4 to the Misfire rate when the loaded round is fired. Prerequisite: Weapon Proficiency: Firearms.

Basic Gun Types


A slow-burning match is touched to the flashpan when the trigger is pulled, igniting the main charge and firing the bullet.

Misfire: 1-5
Price: 50gp pistol 80gp musket


A piece of flint strikes steel when the trigger is pulled, sending sparks into the flashpan, which ignites the main charge and fires the bullet. Less prone to misfiring than the matchlock mechanism.

Misfire: 1-4
Price: 70gp pistol, 120gp musket


Catch-all term for various forms of magical mechanisms. All that is needed is a spark from a minor enchantment. Higher-end models can also keep powder dry, improve accuracy, reduce the chance of a misfire, etc.

Misfire: Generally 1-2
Price: 350gp pistol, 400gp musket, for a very low-end model (“Are you sure this is magic?” type of thing). Could go much, much higher.



Your average, handheld black-powder weapon.

Damage: 2d6
Range Increment: 20ft
Weight: 3lbs
Damage Type: Piercing
Critical: 20 x3


Useful for volley fire, longer ranges, etc.

Damage: 2d6
Range Increment: 40ft
Weight: 3lbs
Damage Type: Piercing
Critical: x3


The sniper’s choice.

Damage: 2d6
Range Increment: 80ft
Weight: 3lbs
Damage Type: Piercing
Critical: x3

Special: Reloading this weapon takes an extra round.

What cunning instruments are these…

Dragon Gun

Meant for shooting at dragons (hence the name). Very large bullets, very heavy gun.

Damage: 4d6
Range Increment: 30ft
Weight: 7lbs
Damage Type: Bludgeoning
Critical: x3

Price: 500 gp Matchlock, 800 gp Flintlock

Special: Rolls d10 on misfire table.

Load up whatever you have on hand and shoot it at someone. Blunderbusses do not need to use bullets, and cannot be loaded with cartridges.

Damage: 3d6
Range: Special: 15-foot cone
Weight: 3lbs
Damage Type: Piercing

Price: 100 gp Matchlock, 250 gp Flintlock

Special: Firing a blunderbuss does not require an attack roll (though you must still roll for misfire). Everyone in front of the firing individual must make a reflex save or take the damage. Reloading a blunderbuss is as a musket.


A tiny gun that fires a tiny bullet–but no one knows you have it.

Damage: 1d6
Range Increment: 10ft
Weight: 1lb
Damage Type: Piercing
Critical: x3

Price: 120 gp

Special: Slight of Hand checks made to hide a derringer get +4. Cannot be Matchlock.

Deplorian Special (Prototype)

An earlier version of the Deplorian Special, rushed to production due to the demands of the customer.

Damage: 3d8
Range Increment: 30ft
Weight: 5lbs
Damage Type: Piercing
Critical: 19-20 x3
Misfire: 10, rolls d10+5 on misfire table. Any result of above 10 is treated as a 10.
Ammunition: Flechette cartridges


A stream of burning oil gushes from the brass maw of the demon’s head. Brought to you by the skillful hands of Lucas Deplorian.

Damage: 1d6+2, and 2d4 fire damage for each round until they manage to put it out
Range Increment: 20ft, less if it’s windy
Weight: 5lbs
Damage Type: Fire
Critical: x2 19-20
Misfire: 4, rolls d10 on misfire table
Ammunition: Flammable oil


Black powder required to fire a bullet from a

Dragon Gun: 1 ounce (437.5 grains. Might round this to 400 or 450)

Musket: 80 grains

Pistol: 40 grains

Derringer: 20 grains

Grains of powder in a pound: 7000

Bullets x10: 1sp
Black Powder (15lb keg, 105,000 grains): 220gp
Black Powder (2lb horn, 14,000 grains): 30gp
Paper Cartridges x10: 2gp (not including powder and ball)

Paper Cartridges, Preloaded x10: 5gp (includes wax paper to reduce chance of powder getting wet). Reduce misfire chance by 1.

  • reply Laurence Perkins ,

    A couple of minor suggestions to make things more believable:

    First, a full ounce of powder is the hottest charge used by a 4-bore elephant gun. The bullet is about an inch in diameter and weighs between a quarter and a third of a pound. This weapon has a muzzle energy of 13,567 foot pounds and a recoil force in the 200lb range. For reference, a 30-’06 has a recoil force of less than 50lbs, and a muzzle energy of only around 3,000 foot pounds. I would only expect to see a weapon that uses a full ounce of powder in the hands of a dwarf, or an exceptionally burly human. (Possibly an orc if you could find one that was temperamentally suited to using it) Basically, it’s your dragon gun. I’d probably make it take a strength check to not get knocked on your butt when firing it.

    A .60 calibre rifle shoots comfortably on 80 grains of powder. There are 7000 grains to the pound. A pistol usually uses 40 to 50 depending on type. A derringer would use 20 to 30.

    Second, a flat 33% chance of hitting an ally with a hangfire is idiotic. The first rule of using firearms is that you don’t point them at your friends, especially when they’re malfunctioning. I would think that having the firearm proficiency feat should let the player make a concentration check to maintain their aim and turn it into hitting an enemy or a miss. Of course, that means not defending yourself against any counter-attack.

    You did manage to get your loading times about right. 🙂 A reasonably dexterous person can usually manage two rounds a minute. A trained man can do three. An expert can often manage four if he doesn’t have to take too long about aiming.

    Have fun. And don’t forget, a powder horn, a candle, and a string can make a rather effective booby trap. 😉

    • reply Adam ,

      I will admit that the “ounce of powder per shot” thing was something that I made up when I couldn’t find good information on how much black powder was generally used to propel a musket ball. I’ll use your numbers–I’ll assume you know more about guns than I do, which wouldn’t be hard–though that means I’ll have to rework my pricing numbers a little bit as well.

      Your idea for hang-fires is much better than mine, I will admit. My current system comes from me really not knowing how to represent it in D&D terms. The idea of a concentration check is a good one, and I’m thinking that you could even use the check as a second attack roll to determine whether it hits or not. Doing so would leave you open, though, as you said, which seems to me like it means you’d lose your dex bonus to AC.

      Since you seem to know a lot more about black powder weapons than I do, do you mind if I ask a few questions? Thus far I’ve been assuming that pistol and musket ammunition is largely interchangeable, but already the different amounts of powder that you’ve given me change that. I was wondering, do you know if there’s any difference in the size of the bullet fired from a pistol vs a musket? I’ve been having them deal the same amount of damage, but if they’re being propelled with less force and are possibly a smaller size, I may have to change that.

      • reply Laurence Perkins ,

        Bullet sizes between pistols and rifles are often the same. This is usually for simplicity since that way you can get a matched set and not have to carry multiple types of ammunition. Also, any ruined long barrels can be cut down into pistols. If using the same powder in each the pistols tend to be less powerful the same way that a shortbow is less powerful than a longbow. However, most people use a more finely ground powder in a pistol so it burns faster, making it possible to get almost the same amount of power out of the shorter barrel. (One die-class lower than the same calibre of rifle is probably acceptable for a starting point. Two if using rifle powder. Adjust it from there based on play experience.) However the pistol will be less accurate than a long-barrelled gun. You can simulate that by giving it a shorter range increment.

        20 to 30 feet is probably about right depending on the quality of the pistol. The musket should be about as accurate as a crossbow, which has a range increment of 120 feet. The slight decrease in projectile stability is pretty well offset by the increased velocity decreasing the effects of wind and the need to adjust aim for range. Most blackpowder rifles have their sights set for up to 100 yards, or 300 feet. The tradeoff is that, until your world has invented hollow-base ammunition, the rifle will take longer to load than the musket. A common trick is to use undersized ammunition that can be loaded quickley, but yields the same accuracy as a musket, and then wrap a piece of cloth around the ball to tighten things up when you have time to load carefully or need the accuracy.

        Different bullet sizes yield variations in power, but also fairly sizeable differences in weapon weight. The 100 calibre elephant gun I mentioned in the first comment weighs almost 30 pounds. A 62 calibre Baker rifle weighs about 9 pounds. Sadly there’s no hard and fast rule. Your best bet is probably to look up weights and muzzle energies for the 4-bore, the 8-bore, the Baker, the Brown Bess, the Harper’s Ferry, the Kentucky Rifle, and the Derringer and use them as reference points for what to create. If you want to get really fancy, look up the Girandoni. Was in a campaign a while ago that included a Dwarven Druid with a breech-loaded 4-bore and an artificer with a Girandoni. It takes an innovative DM though to balance a campaign with that much firepower.

        If you wish to be cruel to the victims of your new weapons, most blackpowder firearms produce a “rooster tail” of fire that’s about as long as the barrel itself. Anybody within that range takes fire damage and is permanently disfigured by a “blackpowder tattoo” caused by particles of soot being forced under the skin.

    • reply Jon ,

      Your paper pricing is way off. In the DnD world [Taken from a 3.5e Player’s Handbook under equipment) you can get a sheet of paper for 4 sp, and that is paper not parchment which is cheaper. Using reenactment information on making a paper cartridge you should be able to get 4 cartridges out of a sheet. So made yourself you are looking at around 1 sp per or 1 gp/10. Retail maybe 2 gp/10.

      • reply Adam ,

        That’d be for the paper, yes. I was including the cost of powder and ball in them.

        Looking over my price list for ammunition, however, I seem to have forgotten to change the prices to account for the information Lawrence Perkins gave me in the comments above. You are right in that paper cartridges wouldn’t cost nearly as much as I’ve written; also, there should be different costs for different types of firearm. I think I’ll have to rewrite the whole price list, now that I’m thinking about it. I’ll do that tomorrow.

        I haven’t really looked at this material in a few years–I’ve been running Shadowrun instead of D&D lately, which of course doesn’t really need more guns added to it. Thanks for bringing it back to my attention, that little discrepancy would probably have been there forever if you hadn’t.

      • reply Critter Maze ,

        Powder back in the day was not as good as power is now.. Once ouch both in the barrel and in the pan could be doable… I will go with the first rules and modify to the second set if they get … magically enhance powder or what ever I can think up… I like this page..thanks for post

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