It's a gun that shoots rocket dogs.

There are two guns that shoot rocket dogs.

Infinite ammo, full auto, has a sniper scope, barks when fires, small Liberty Prime explosions when it collides.

Can be found in Chet's general store in Goodsprings, takes no ammo.  AwesomeDogSniperShotgun is a full auto sniper rifle that fires 10 dogs per shot. Works more or less like regular bullets.  Awesome Dog Cannon is a FatDog Launcher.  Smaller AOE than a FatMan.

Mod requires nothing more than the base game.

Two guns now.
awesome dog cannon - xx000DC0
awesome dog sniper shotgun - xx00109E

If you're updating, unequip the old gun first, save, update the mod, load, you'll have to buy the guns again from Chet or use the console.