You first need:
3.A mavreick barrel
4.Longshot pistol barrel.
5.A small flat head screwdriver.
We got work to do.
First you need to take out the ars in the gun. There should be little vent like things. Take those out with a screwdriver. Then take a dremel and sand it to make it a hole to fit the barrel.
Now take you Mavrecick barrel and roll duct tape around it. Then shove it in to the titan's barrel.
Now you are finshed. All you have to do shoot it is to put one bullet in the mavricks barrel and pump it. Or to make it a scatter cannon put 4 darts in then pump and fire. So there you have it a scatter cannon.