I'll be using rocket sidewinders for bear this fall. I used the same head last year and got complete pass through on a 325lb bear. The bear was broadside, maybe quartering a couple of degrees. The arrow went in behind the shoulder and came out the upper leg on the other side. One of the blades imbedded in the bone in the leg and broke away from the broadhead. This is what they are designed to do, either bend back of break off when encountering very large bones so that the rest of the head can continue on and exit.
I think six out of seven hunters in our group used mechanical heads and some of those guys have multiple kills with them.
Oh yeah, my arrow has 72 ft. lbs of k.e.