I've been using the factory medium rings on my carbine for several years. I hunt feral hogs year 'round and also take axis deer, whitetail deer and the occasional loose exotic game animal. I've never had a failure of the rings or loss of zero, even when a rock thrown by a utility vehicle smashed the lens of the scope on the the carbine at the time. I average 50 to 60 shots on game, with my carbine, every year and another 100 rounds or so at the range. The wife and I spend at least 2 weekends a month on the family ranch land in the Texas Hill Country. I walk several miles over the weekend carrying My 527 Carbine or an old Ruger 77 RSI in 250 Savage. Both of the rifles have fixed power 4x scopes mounted.