I shoot 500s out of my 60 lb Hill bows and I have the arrow at full length and 75 grain insert with 200 grain broad heads and field points with the Easton aluminum broad head adaptors over the end of the arrow. Fletched with 3, 5 inch feathers. They fly great ! I have a 29 inch draw and the are not underspined even with all, that point weight. I tried the 600s but they were a little weak. I shoot standard split fingers. The finished arrows weigh in at a few grains over 600 if I remember right. By the way the Easton broad head adaptors keep the wood grain carbon outer strips from peeling up when shot into stuff and really makes them indestructible, I peeled a lot of outer layers off the arrows before i bought these little black aluminum pieces of gold. Great things they are. Look at the suggested size for whatever MFX you get , I bought mine from 3 rivers.