ive never had one fail either but mostly because they sit in the junk scope box and are never used and pulled off a gun as soon as it comes in the door. Same thing with the old weavers. I know some love them but ive had them fail more then any other scope. Mostly no doubt do to there age and the seals being dried up. But you couldn't give me an old k weaver. Today you can buy a decent import scope from cameraland or optics planet for a 100 bucks that would put a vari x2 leupold from 20 years ago to shame. Why would you even bother with something like a used tasco on a big game gun that might cost you the trophy of a lifetime. Maybe on a 22 but even then it would be a cheap 22!