Rod,
The arrow and BH are a matter of personal preference for the most part, however, if you are worried about penetration, other than optimal shot placement, a Cut-on-Contact, like the Magnus is probably the way to go. Make sure the bow is tuned to perfection, and remember to hold low in the vitals, esp. if either of the ones you lost jumped (really ducked, not sure why we called it "jumped") string. I try to always remind myself to aim for the heart, sometimes esp. if I'm not perfectly sure of the distance, if I don't get a chance to use my Rangefinder, I estimate the distance, plus a little and aim for the heart. I personally like a mixed batch of mechanicals and fixed blade heads, but if you've had penetration issues (especially on well placed shots), I think the last thing you want to be shooting is a mechanical BH. Also you want to make sure you have a fair amount of weight to that arrow, make sure you're shooting something around the 400 grain, or heavier, for a little better penetration. Hope some of that helps a little. Better luck next time. I hate that sickening feeling of losing one.