From what I've seen, there are three kinds of scope "failures."
One is from accumulated recoil. I've never busted one from recoil, but I've seen friends, who shoot lighter, heavy recoiling magnums have scopes stop holding zero.
Another is from impacts. I've bounced lots of scopes off of rocks during falls etc. w/o damage. I've seen some shift zero. In at least one case it wasn't the scope at all but the front scope ring loosening.
I suspect this type of failure is also cumulative. The reticle on my old 4X Leupold gave way during some rough bolt slaming which was alot less than what it had previously endured in the field.
Last of all is failure to change zero as expected or return to zero. I understand the military teaches their snipers to shoot their rifles often and always considers the first and last shots to be the most important. LEO snipers have apparently adopted this philosophy as well.
So, all of this means what ? It means when you buy a new scope, first make sure it's mounted right. I've seen far more mounting related scope problems than actual scope problems.
Second, test it for 60 plus rounds and to make sure it works right. Even the very expensive, highly regarded makers can produce a defective scope.
Third, be aware of what kinds of failures scopes or mounts can have and watch for them. Again, test your rifle and scope combination from time to time.
When you find something that works well, stick with it. I've got several scopes who have been very reliable whose rifles are long gone. But I keep them. They may not be the brightest and have full multicoating. Two even have too little eye relief and not near enough eye box. One doesn't have much of a reticle for low light shooting. But I keep them anyway because they alwayts worked even when abused. E
