How do you cut off the front part of the nerf longshot?

i am trying to mod my nerf longshot so it will look like a battle rifle from halo 3.i have been watching videos and i see that they usually cut off the the front barrel part(not with the pistol on just regular without pistol attached)so that the front part will be flat and go straight down and not have the big barrel there.how do they cut it off?do you just saw it off or somthing?