make sure you have enough speed if its a big gap, casing cannons hurts like a mother. first of all, approach it with said amount of speed, pop and do your 90 like on a normal rail, land with a legs at shoulder width and make sure to put enough weight on your front foot so the speed doesnt make you slip backwards because, once again, that hurts like a mother. when you get to the end, pop and spin if you want to or if you have enough speed you can probly just slide off.