You need to use a high quality loop material, DON NOTUSE WALMART LOOPS they will stretch alot and are stiff.Look at thislink and buy the good stuff (
http://www.archerytalk.com/vb/showthread.php?t=353639&highlight=d+loop+mater ial). This material is top quality with little to NO stretch and dosent cost much and you will receive it in a few days.