A Curiously Energized Crossbow that uses no strings to fire. A gun perhaps? NO! 
     Elric, The artificer, crafted this masterpiece by capturing the spell "Gust of Wind" into a capsule and pressurizing it, he is able to fire both sling bullets AND crossbow bolts. Weaponizing the gust of wind spell allows for an extra thump on each shot. Though, it is still his first design and heavily dependent on magic. thus, is prone to it malfunctioning in anti-magic zones.

-This weapon functions as either a sling or a heavy crossbow. This weapon uses dexterity for both attack and damage rolls.

-You have a +1 bonus to attack and damage rolls made with this magic weapon. The +1 damage enhancement is calculated as force magic damage

-This weapon is magically charged via arcane energy. Loss of magic/ anti-magic zones or being disarmed renders this weapon useless.

-Reloading this weapon takes a standard action (although rapid reload rules still apply)

-This weapon can be loaded with magical bolts or magical bullet for the sake of damage but only deals an extra one point of force damage per attack otherwise.

Price- 2250

-H. Crossbow stats

Med

50 gp

1d10(peircing)+1(force)

8 lb.

5.

Sling stats

Med

—

1d4(peircing)+1(force)

0 lb.

Proficiency with a Heavy Crossbow allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Damage: Force, Damage, Combat, Ammunition, Heavy, Loading, Range, Two-Handed, Push