B.F. Blunderbuss

Rain of bullets. The weapon's range is a 15 ft. cone, where creatures caught inside can try to avoid damage, cutting it in half, by succeeding in a DEX (DC=8+DEX modifier+profiency bonus) saving throw. 

Big money no whammies. The weapon can still both missfire and score a critical hit. Roll a d20 upon firing to determine the outcome.

Ammunition.  The size of the cannon alows for many things to be loaded into it, such as nails, stones, splinters, ball bearings and any other kind of scraps. With damage as follows

• Nails: 2d8 + (DEX modifier) piercing damage
  
• Ball bearings: 2d8 + (DEX modifier) bludgeoning damage
  
• Splinters: 2d6 + (DEX modifier) slashing damage
  
• Stones: 2d6 + (DEX modifier) bludgeoning damage
• Others: DM's discretion

That a kick! The weapon is powerful, upon firing, the user will recibe a strong recoil, suffering 1d6 (add 1d6 at level 5,11 and 17) bludgeoning damage and being pushed 5 feet. A successful STR (DC=to "Big money no wamies" d20) saving throw will half the damage and avoid the push. If the weapon missfires, "That a kick!" does not take place. If the weapon scores a critical strike, the recoil damage and push will be doubled.

 

Firearms are a new and volatile technology, and as such bring their own unique set of weapon properties. Some properties are followed by a number, and this number signifies an element of that property (outlined below). These properties replace the optional ones presented in the Dungeon Master’s Guide. Firearms are ranged weapons.

Reload. The weapon can be fired a number of times equal to its Reload score before you must spend 1 attack or 1 action to reload. You must have one free hand to reload a firearm.

Misfire. Whenever you make an attack roll with a firearm, and the dice roll is equal to or lower than the weapon’s Misfire score, the weapon misfires. The attack misses, and the weapon cannot be used again until you spend an action to try and repair it. To repair your firearm, you must make a successful Tinker’s Tools check (DC equal to 8 + misfire score). If your check fails, the weapon is broken and must be mended out of combat at a quarter of the cost of the firearm. Creatures who use a firearm without being proficient increase the weapon’s misfire score by 1.

Explosive. Upon a hit, everything within 5 ft of the target must make a Dexterity saving throw (DC equal to 8 + your proficiency bonus + your Dexterity modifier) or suffer 1d8 fire damage. If the weapon misses, the ammunition fails to detonate, or bounces away harmlessly before doing so.

Ammunition

All firearms require ammunition to make an attack, and due to their rare nature, ammunition may be near impossible to find or purchase. However, if materials are gathered, you can craft ammunition yourself using your Tinker’s Tools at half the cost. Each firearm uses its own unique ammunition and is generally sold or crafted in batches listed below next to the price.

THIS IS UNOFFICIAL MATERIAL

These game mechanics are usable in your campaign if your DM allows them but not refined by final game design and editing. They aren’t officially part of the Dungeons & Dragons game and aren’t permitted in D&D Adventurers League events unless otherwise stated.

Notes: Weapon Property: Range, Reload, Misfire