Well, I don' t trust his numbers ' cuz something is plain fishy.
No problem with a 600 grain 2219 with a 128 grain point. That' s simple. Cut it 30" long, 4" vanes and a glue on nock and you' re there. You' d have an FOC a shade under 9%.
Where I think he' s full of meadow muffins is with the 400 grain arrow. The only way he can get a 2213 down to 400 grains with a 128 grain point is by cutting it to 23" and using 2" feathers. Such an arrow would have an FOC of 15%.
The 2219 would be spined for a bow from 45 pounds on the low end to 60 pounds on the high end. A 23" 2213 would spine out somewhere around 100 pounds.
I don' t care how much adjusting you do, the same bow would not shoot both those arrows with anywhere near the same efficiency. Especially considering you' d be shooting the 2213 off a pretty healthy overdraw!
So, even if he did get the weights he claims, and got the speeds adjusted to give equal KE, with an 18% difference in momentum (.4348 vs .5355)... he' s got a 40% difference in FOC! Couldn' t someone just as easily say he proved that 40% HIGHER FOC gives as much penetration benefit as an additional 18% in momentum?
Art, Doesn' t Holt' s argument prove that a heavier arrow is more preferable to a lighter arrow, as the heavier one will always have a higher level of KE for a given bow?
That' s something else he ' proved' without intending to: A heavy arrow at the same KE (at less draw weight) will penetrate as well as a lighter arrow.
He also might have proved that a short, light, incredibly overspined arrow might penetrate every bit as well as long heavy arrow at the prescribed spine.
Or he might have proved that an arrow with 2" feathers will penetrate as well as an arrow with 4" vanes.
Or he might have proved an overdraw arrow will penetrate as well as a full length arrow.
I have great respect for Dave Holt but I don' t buy into everything he says. IMO, he set out to prove a pet theory and so he did what he had to do to ' prove' it. Proven, at least, to those who don' t question the methods. He left too many variables wide open and unanswered.
And then, even if you account for all the variables, one question remains to be answered... Does penetration in styrofoam or ethafoam correlate in any way whatsoever to how arrows will penetrate in actual flesh? I think NOT.