Ive used them before. I had a bad experience with penetration. My buddie was using them at the same time and had a penetration problem as well. I find that these heads that have to flip all the way back to their cutting cupacity are not so good. You loose alot of enery on angles and if you hit a shoulder (which you shouldn't) but if you do, your screwed. Just my opinion, I use stingers, fly like field tips and are the sharpest head out there.