Just received a dozen of these arrows and have to say I love them already. The physics of the arrow tapering, increasing the FOC is pretty awesome. I have noticed an increased depth the arrows are penetrating the target. I also love that I don't have to add weights to the inserts to increase FOC. Some of my specs for reference. 27.5 inches 5mm FMJ - FOC 10.91% and arrow weight 415 +- grains. (NAP 100 gr Killzone) 27.5 inches T64 FMJ - FOC 13.64% and arrow weight 509+- grains. (NAP 100 gr Killzone) That's some knock down power at the point of impact!