I too have a bunch of older Weaver scopes and like them all...I have 3 3-9x Marksmans, 2 K4's, 1 K6, and 1 K2.5...I have them on everything from 280 Remington,30-06, and the 2.5 is on a Marlin 1895 45-70...They have all held up well and all hold zero just fine...I am not sure but I think the steel tube has a lot to do with their durability...I have used scopes with better light transmission like the Burris and the Nikon, but overall, for what you pay for a Weaver on ebay, usually around $60, I don't think you can get a better scope.