I have been shooting the Axis arrows and are 9.2 gr per-heavy. I shoot 70 lbs and slick trick 100 gr bh. The new bows are a lot faster and you can get lighter. My new rig, being built now, has one shooting at 51.7lbs 345fps with a 6gr per. He used the proto type on an Elk and got complete passthrough. I never not had a complete passthru even at a doe this year at 38 yds and hit the spine, thought it was further. Shot a buck at 12 yds thru the shoulder blade and thru the femur bone on the other side and stuck in the dirt. That is why I like the heavier shafts, but spine is just as important. With my new rig I will be shooting tapered shafts and they will be lighter, with more FOC.