[Yo-Yo]

Oops! FBI uses chain saw on wrong door

So there really is a use for the Tactical Chainsaw Picatinny Rail Mount Accessory.

[MaxMax]

Nice. As a RL mech tech I could easily make one of those. Now, whether or
not it would be legal to attach to a firearm is the question. An electric
motor wouldn't be all that noisy and easily fed electrically from a
lightweight motorcycle battery into 115v. Even a small lithium pack
would seem to power it for at least a couple creative Zombie kills depending
on the horsepower.

Personally I would go for a shorter blade to make cornering quicker
for that special downward zipper effect.