for my heavy bows I used to use the same thing Bob Swineheart used. A light rope, a little thicker than my bow string. It had a cup sleeve on the bottom end and a slightly large bow loop at the top. When I loaded the bow, I held the bow string snug up against the thicker loop, then as the pressure was let off,the bow string slid under it and into the string slots forcing the thicker loop out. Used it for years on the super heavies, without even one slip up. I cannot say the same for the ones with the leather cups on both ends, I have gotten into a couple of wrestling matches with them.