I want to hijack this thread for a moment and offer my sincerest apologies to Sylvan for my overeaction to his earlier comments, because it is obvious that he is correct in his assertions regarding physics and my observations.

But, my observations were still accurate. After some thinking and some input from an industry engineer I think I have found where I inadvertantly slipped an orange in an attempted apples to apples comparison.

When making and weighing the arrows I used for my testing I used ACC hyperspeeds for the 340-360 grain arrows (in 5 grain increments) using nibb points which have a very stiff dynamic spine. For arrow just heavier than these (365-400) I used Bemans ICS which had the needed weights, but were dramtically underspined or the application. I believe because of the spine differences, the heavier, weaker arrows were receiving less of the bows energy resulting in inordinantly slower speeds, while the lighter stifer arrows were able to receive maximal energy from the bow resulting in SLIGHTLY higher KE #'s for the lighter arrows. If the heavier arrows had been adequate in spine they would have shown better speeds and had the expected higher KE than the lighter arrows.

BTW, Sylvan, I pretty much agree with your assessment of the whole KE vs M debate. I'm not sure but I think somewhere in one of the previous thread mentioned I only use the light arrows to play with in front of the chronograph, and choose to hunt with fairly heavy slow arrows.