12-Gauge Chainsaw ''Brandello''

BRANDELLO

12 Gauge Pump action shotgun, designed to be used with chainsaw bayonet attachment. Set to full choke to avoid damaging the Chain.
Shotgun itself has an internal magazine that holds up to eight round. Equipped with Basic Holographic optics and a Weaver rail mounted on a Shrouded barrel with exhaust ports to combat overheating.

The Chainsaw bayonet is removable and can function independently from the Shotgun, The handle of the chainsaw Mounts into the Pump and locks into place with a simple catch mechanism designed to allow for easy removal of the Saw in combat, the brake lever functions as a throttle for the saw while also doubling as a hand guard.

If you're wondering how the chainsaw is powered, So am I. 
I was thinking maybe a battery pack situation? Although that seems ridiculous to me.
But at the same time I can't see a normal combustion engine being compact enough to work.
So lets just pretend that it runs off Love and Sunshine, right?