Challenge isn't easy.
What Mason said is probably the easiest way to get it done as the hand cannon, shotgun, and heavy machine gun allow you to play normally.
Having a group to run crucible also helps as you don't have to worry about the objective, and you can focus on just your own kills.
When I did it on my hunter, I basically ran the swordbreaker and corrective measure. I would just steal the ammo crates whenever I saw one. It's a real grind, but once you get Thorn its pretty nice (unless the nerf kills it again).