The Insane-brand Chainsaw is a red chainsaw. The weapon does a medium amount of damage per slice, but has unlimited ammo. It's limited range prevents it from being used from any range beyond short range.
The golden version of this gun does double damage.
The Chainsaw's limited range makes it useful as a close-quarters weapon. It can tear though weak enemies quickly, making it handy for eliminating nearby weak enemies without having to use up ammo for other weapons.
The Chainsaw's somewhat-low damage makes it a poor choice to use against stronger enemies. Other weapons would do much more damage at the Chainsaw's range against those enemies.
It also works well as a person defense weapon when placed on the very bottom of a stack. This lets the player kill any weak enemies that approach them while preventing them from wasting ammo for other weapons or being in danger of an explosive weapon hitting the weak enemy when its near the player, harming the player.
This weapon works very well when paired with the 0-4377 Flamethrower. Both weapons are built for close-quarters and supplement each other's weaknesses. The Chainsaw can harm the closest enemy to the player, while the Flamethrower will damage any enemies just past the Chainsaw.