If you shoot a C on C blade, it takes very little energy to penetrate the animal. With an expandable, it takes much more. One year, my hunting partner shot a spike elk that was feeding in a meadow. It raised it's head, looked around and then went back to feeding until it fell over. He was using a Bear Razor. It used to not be uncommon to shoot an elk, it would trot off and then you could bugle it back. That sort of thing probably never happens with an expandable. I've yet to have a cut on contact blade not pass thru an animal. I know of rifle hunters that have to shoot an elk multiple times to bring it down. An arrow shot thru the vitals generally only takes 1 shot. I believe it is the "slap" that they feel as the bullet expands which gets the adrenalin flowing. An animal can run a long ways on adrenaline. I personally don't credit arrow weight with anything important except arrow noise reduction, speed and momentum. When using a cut on contact broadhead, momentum is really low on my priority list. It just isn't an important factor. I find an arrow combination that works well for the quarry I am hunting. I have killed deer, elk, antelope, bear and hogs. Always a pass thru when using a C on C broadhead. Generally my arrow total weight ranges between 350 grains to 386 grains. I have a 30 inch draw and until 5 years ago or so, I shot 70 lbs. I now shoot 62 - 65. The age factor has won out.