--Gatling Gun -- and MODIFIED weapons (not for troops!)

[insomniac]

Hi can I have a detailed instruction on how to use cannons and gatling guns? They are a mystery to me. I manage to drop them on the ground but don't know how to aim or fire the weapons. I load up the cannon/gatling piece as well as cannon shells like I would a weapon. I haven't seen any ammo for the gatling gun. Please help it would be cool to use them 

that is something i wonder too. I couldn't it get it work

Also there is no special gattling ammo in the markets