Will do Willie, (maybe more like 7 after recalculation finished arrow) hopefully next weekend if all going to plan. I've only shot lighter arrows similar to these but with a lower spine with heavier heads(long type 10, the longer and heavier version of these arrowheads) off a lighter 100@31 bow...they flew well but the foc was greater. These arrows are spined around 115 and I'm shooting a 125@31, I'm hoping with the lighter heads they won't be too whippy, I got a good feeling they will be ok, how good will be all trial and error and just trying for a good 3/8" target arrow rather than the usual 1/2" shaft tapering to 3/8" at the nock.
FOC is a relatively new concept for me and something I'm starting to consider more. Anyway, as soon as I can I'll post how they perform.
(I think in general most warbow arrows by design have a high foc for penetration, save for flight arrows.)
R.D.