I know there is a point where arrow mass will exceed a bow's capacity to shoot efficiently, but I would expect it to be far heavier than Mean V's results show. I have to look at the data though, and look at it with an open mind.

MeanV says his bow shoots a 500 gn arrow with less KE than it does a 400 gn arrow. Yes, the results are odd, it seems way too light of an arrow to show a dropoff. But that's what his testing shows. Was it an aberration? Would KE have gone back up if he'd gone further and shot a 600 gn arrow? I don't know. He didn't test and we have no hard data to prove otherwise. I certainly have had my disagreements with the man, but I respect him enough to take his test results seriously.

This is not the first time I've heard of this happening though. I've had similar reports from several other knowledgeable people in the past 5 years or so; different bows, different manufacturers. I think perhaps the manufacturers are building designs nowadays that are more efficient at shooting arrows weighing 350-450 grains because of the mass stampede to carbon arrows. That is the weight range most people are shooting these days, and naturally they all want to put out those high IBO ratings to get people to buy their bows. I think it's just possible that loading up efficiency on the low end of the weight scale has the effect of sacrificing efficiency for heavier arrows. It's the only logical conclusion I have for a KE dropoff with arrows as light as 500 grains, but I've not yet seen the whole picture.

You see, unfortunately, in each case the shooter did what Mean V has done. Once he saw the KE drop for an arrow weight, he didn't go on to test an even heavier arrow. So we're still in the dark as to whether the drop was only for that particular weight and would have risen for a heavier arrow, if it was the beginning of a downward trend in KE. More testing needs to be done. Until someone does it though, we don't have enough data to draw any firm conclusions.

Another small point... When looking at bow test data, keep in mind that the KE/arrow weight graphs have not been drawn up with hard data for every arrow weight shown. As noted earlier, it's darn difficult to test a wide variety of arrow weights without needing to do some serious retuning for different arrows. If you read the fine print, what most often happens is the tester has used 2 different arrow weights (usually 5 gpp for IBO and 9 gpp for AMO) to establish a line on the graph, and the KE figures for all other arrow weights are extrapolated off that line. Line graphs are handy tools for making estimates, but hard data from actual testing trumps estimates, every time.