I shot grim reapors last season. It was my first time to ever use mechanicals of any any kind. All my hunting pals have shots Muzzys for years, myself included. We were all AMAZED with the holes the grim reapors put in whitetails. Although I never had any problems with Muzzys, I won't be swithcing back any time soon. I killed 4 deer with the Grim Reapors last year, and hope to kill many more. Best thing IMHO is no o rings or rubberbands.