I agree with Hoytman. I believe a pass thru arrow aids in many ways.

First, you have your arrow to inspect after a hit. If the deer makes it out of sight or earshot, this is a big part of how I decide what to do next. Hopefully, I also have a visual of where the arrow hit.

Next, as we all know, arrows do not kill by impact shock, and tissue damage. All we need is for the broadhead to cut major blood vessels. A pass thru does the cutting we need and at least some of the arrow`s energy is wasted, imparting less shock to the animal. Hopefully, this will bring about less of a reaction and the animal will not run as far before it stops to survey the situation. Seconds tick by, and your animal is down. Blood or no blood, less travel from the point of impact, to the animal, increases the odds of locating the animal easily.

In addition, I believe that a whitetail is very aware of an arrow protruding from its body, and that at least sometimes, this fact will prevent them from stopping until they can go no more. I think it`s safe to say, most everybody is aware of how far a whitetail can run in fifteen seconds without stopping, even in heavy cover.

Lastly, two holes are better to bleed from, especially if the shot was from an elevated position. I like drain holes.

Forty pounds WILL do what you need to get two holes in deer, but I would keep my shots close, and wait for a relaxed broadside shot. But then again, thats good advice with eighty pounds as well.

Bentpole said what I wanted to say, with a lot less typing.