And my tests had nothing to do with performance on game. They were simply measuring the amount of penetration (depth) I could get with different arrows in a consistent medium. The problem with any of these tests into a medium like foam or any other target is that the thing is designed to stop an arrow by use of friction. You can't quantify things and say that if I shot an arrow with X amount of KE and momentum I would get this amount of penetration. And if I doubled that figure I would get twice the penetration. It won't work that way, I tried.
Paul, you've pointed out the key. Foam target penetration has no correlation to penetration on game.
What I did notice is that there is a definite difference between light arrows and heavier arrows out of my bow. And I don't need to measure it to know it. When I was doing some tests shooting at a 3-D target you could hear and see the difference between the two arrows at 20 and 30 yards. The heavier arrows hit the target much harder and actually rocked it after the shot. The lighter arrows (300-350 grns) didn't hit as hard or move the target. This tells me that the heavier arrows carried more energy to the target for sure.
This is something that is very obvious if the weights are significantly different. I've been using arrows around 650 grains out of my compound while shooting 3D. Some of the guys I shoot with are around 380-420 grains with their arrows. The difference in target movement is so obvious that everyone notices it right away. It's not a little more movement - it's a lot more. And I'm using a slightly lighter draw weight than these guys!
If someone wanted to determine KE and momentum on some arrows, it does no good to measure it two feet from the bow. The crony should be set at 25-35 yards or whatever your maximun range is. Heavier arrows will be far more impressive at hunting ranges. If you're worried about such numbers they are only relavent at whatever maximum distance you might shoot at.
Oh, and I'm not saying, and never did, that what works for someone isn't good enough. I'm simply saying that heavier is better when it comes to arrow stability and penetration on game. If someone gets a thrill out of shooting a fast arrow, I have no problem with it if they know what they're doing. My real hope is that anyone who in unsure of how to best control their arrow or who may be shooting low poundage bows or very short draw lengths, are aware that heavier arrows will give them an advantage.