I do what LBR does with wood, But I cut mine to 30" which gives me a 29" BOP. it took me awhile to find what I need for a spine, even when changing bows, but now I have it, and the spine I shoot works with all my bows. For Carbon, I chose the model, in this case Heratige 150's and cut them down to the length I wanted them at. and since I wanted closeto 160 gransup front, that worked out real well.

All I got to say in what ever you choose, tune the set up, some will say bare shaft and some will not. I did bare shaft once and t didn't work for me. I shoot broadheads when I tune and every time I go shooting, after I get the field point arrows flying good, I then shoot a broadhead arrow to see if the set up is really tuned.