'Trusty Betsy', the Two-bore Blunderbuss

An over-sized firearm, constructed by a gunsmith as an exhibition piece rather than as a functional weapon. It weighs almost 25 pounds in its unloaded state, making carrying it rather awkward, to say nothing of firing it.

It counts as a simple ranged weapon (range 10/30) with the two-handed and heavy properties. It deals 28 (8d6) non-magical piercing damage on a hit. Attacking with this weapon uses your whole Attack action, regardless of your other features.

When you fire this weapon, make a DC 12 Strength saving throw. On a failure, you take 7 (2d6) bludgeoning damage from the recoil.

If you roll a natural 1 on the attack roll, the weapon explodes as if you had cast Fireball (DC 15) centered on yourself. This destroys the blunderbuss. After it has been fired, the blunderbuss requires a short rest and 5gp worth of materials to reload.