Here was the most recent rules I was working with. This was intended for a setting around the Napoleonic/Age of Sail era when guns are just plain better than other ranged weapons and armour is on the way out, so the fact that they're more powerful than crossbows/bows etc is deliberate (but I did introduce the Recoil rule so that Str wasn't a totally obsolete stat!). It does make combat very swingy though. A high-level Champion fighter might be critting on an 18, and have three attacks per turn which translates to triple firearm damage base, so would be dealing out a MASSIVE amount of damage with a critical hit. Handling all the weird edge cases that various subclasses throw up is one of the occupational hazards of any attempt to pretty much rewrite a major component of the D&D combat engine like this.
The intent is that guns fire slow but hit hard, and offer some different tactical options to existing D&D ranged weapons. Armour is significantly less effective against them but not useless (otherwise the whole D&D combat maths breaks down). You'd need to eliminate the Gunslinger feat though, it'd make this waaaay overpowered. You could easily tone the damage and range down a bit for lower-tech guns, or if you didn't want to make other ranged weapons obsolete. I was tempted to introduce rules about keeping your gunpowder dry etc, but that's getting all a bit too fiddle, and honestly if you're being that finicky about gunpowder you should do the same with bowstrings. What I'd LIKE to do is come up with some way of reflecting that slow loading times mean that firearms are generally discharged at the start of close combat (or saved for a vital moment) while most combat is in melee. But that requires a generalist PC, and D&D rewards specialisation.
| Type | Damage | Range | Special |
| musket | martial | 1d12 piercing | 150/1200 | ammunition (firearms), two-handed, firearm, loading, recoil 13 |
| fowling piece | simple | 2d8 piercing | 30/300 | ammunition (firearms), two-handed, firearm, loading, recoil 13, scattershot |
| elephant gun | martial | 2d8 piercing | 150/1200 | ammunition (firearms), two-handed, firearm, heavy, loading, recoil 15 |
| boot pistol | simple | 1d8 piercing | 20/60 | ammunition (firearms), firearm, loading, light |
| pistol | simple | 1d10 piercing | 30/120 | ammunition (firearms), firearm, loading |
| horse pistol | martial | 1d12 piercing | 30/120 |
ammunition (firearms), firearm, heavy, loading, recoil 13 |
Firearm - a firearm with the loading property requires two hands to load. A character making an attack with a firearm has disadvantage to Stealth rolls made in the same round. Attack rolls with a firearm gain a bonus of 1d4 against targets wearing medium or heavy armour, or using a shield. A firearm may only be fired once on your turn regardless of whether you have the Extra Attack ability or any other ability that would grant you additional attacks on your turn. Instead, the base weapon damage (including any ability modifiers but not including extra dice to damage from abilities such as Divine Smite or Sneak Attack) is doubled if you can attack twice on your turn, tripled if you can attack three times on your turn, and so on. Any attack you make that is not part of an Attack action causes regular damage, even if you have the Extra Attack ability.
Recoil - a character wielding weapon with the recoil property who moves before attacking in the same round must have at least the listed strength or make the attack roll at disadvantage. If the weapon does not have the two-handed property, the wielder can remove this penalty by wielding the weapon with two hands.
Scattershot - attack rolls with a scattershot weapon are not made with disadvantage when attacking at long range. Instead, damage inflicted by scattershot weapons at long range is halved. Scattershot weapons do not add the usual 1d4 bonus to hit for firearms against heavily armoured or shielded targets.
