HELP with Killing "IT"

U3(IT) is pretty easy to kill. If you're a pro like me you can use your handgun and shotgun on him. It's not recommended, if you suck at it, though. I always try to confuse him in the hallway and I shoot the barrels when he gets near. You can also use the levers to close the gate on him, however his claws will break through them. This is rare for most people, but I've experienced this and it's when he buries underground about halfway dead. Hit the random button combos when necessary and be quick about it, too.

its so easy...
you just run around that rock in the middle...
p.s. "its" name is U3