John I just took a 2200lb bison bull this past December. My arrow set -up was FMJ's with a 125 grain single bevel two bladed Helix Blade. Total arrow weight with brass insert was 525 grain. My elk arrow set-up with different arrows is around 450 grain. My Bowtech RPM 360 definetly favored the heavy arrow with it's patterning in my targets. I cannot emphasize enough about using a good two bladed single bevel head on those beasts. My first shot was from 56 yards broadside and it was a complete pass through. What happened without my knowledge until we were dressing him out was the arrow hit a rib upon the initial entry. The ribs on those animals are no joke. My Helix broadhead hit the rib and continued to rotate and split the rib bone completely and then went through both lungs and out the opposite side of the animal. My second shot was from 45 yards quartering away and penetrated through his left side, through his diaphragm and then one lung and into his right shoulder. Again after dressing him we discovered that the arrow head actually split part of his shoulder blade before becoming embedded. He snapped that arrow in half inside his body when he began to run again. I put a third arrow in him from 20 yards broadside and that was a complete pass through. I really wish I had just let him rest after that first kill shot but he took off and we did not want to lose him in the brush. The last thing we wanted to do was come around a large pinion or juniper brush and have a wounded bull charge usView attachment 23572View attachment 23573View attachment 23574.