Magnum Cannon From Tales of the Comet D&D

 

Another modern style weapon for D&D from The Tales of the Comet. This is all a direct quote so authors and copyright belongs to TSR and then latter WotC. This is the 2E rules but you can convert to which ever rules you use. 

If I used this in a fantasy setting I would describe it as a magical device that spits out metal sling stones. I would probably give it a cool name like Fallen Star Wand, or Spitting Dragon, or Flying Tiger Claws.

Magnum Cannon

The magnum cannon is a high-velocity machine gun that uses a set of barrels to achieve a very high rate of fire without overheating, throwing up a deadly screen of lead. It can be used as a personal weapon, although a rather unwieldy one, but is more often found mounted, either on a tripod or in a turret. Ammunition comes packaged on very long belts that are either contained in a backpack holding 30 charges (for the personal magnum cannon) or in large, 50-charge boxes (for the mounted variety). It requires two rounds to feed a new belt of ammunition into an empty magnum cannon.

Personal Magnum Cannon

Range: 100/200/300 

Damage: 5d4 or 4d10 

Rate of Fire: 1 

Speed Factor: 9

There are two modes of fire with the magnum cannon: short bursts and steady fire. When fired in short bursts, the magnum cannon makes attacks against single targets and is less deadly, but it conserves ammo much more effectively, using but one charge worth of ammo each round. If the magnum cannon is used in steady fire, 5 charges of ammo are consumed per round, but the wielder can “walk the fire,” attacking multiple targets in an area 20 feet wide (with a -4 penalty to hit each individual target).

The personal version of the magnum cannon comes equipped with a harness system that distributes the weight of the gun across the shoulders and hips and uses counter balances to make the weapon more manageable. It is still a rather slow weapon to bring to bear on a target, however, as is reflected in its speed factor of 9.

Mounted Magnum Cannon

Range: 100/200/300 

Damage: 5d4 or 4d10 

Rate of Fire: 1 

Speed Factor: 5 or 2 

The mounted version of the magnum cannon can be operated in one of two ways. It can be fired manually, in which case the effects are identical to the personal version, except that the speed factor drops to 5 (since the operator only has to swivel and aim, rather than manhandle the weapon). Alternatively, the system can be controlled by a computer targeting system. This system has a THACO of 10 and the speed factor drops to 2.

With a computer targeting system, a special form of attack can be made against missiles. To do this, the magnum cannon makes three separate attacks, using steady fire, against any incoming missiles; one at long range, one at medium, and one at short range, in that order. Range modifiers apply If an attack scores a hit, the missile is destroyed and no further attacks need to be made.