I beat him on Normal, Hardcore, and now I am on Insane trying to take him out. I screwed up and I only have a few arrows to knock the kryll out. I was carrying a magnum around for duration of the level until the end where you pick the crossbow up and it only gives you a handful of arrows.
I had it where he was stuck behind a block and wasn't moving towards the side. Had I more arrows I could of taken him out right then and there! Dammit!