Older C79s it was common, and even with later mods it was encountered.
If you have a later mod and use it as a range toy, it is very likely ok, however I just know that when I was in the EO Techs were constantly busy with them.
I've only heard of the DRs having zero shift thirdhand with flipping from 1 to 4 power and back again, not experienced it myself because I can't bring myself to spending that much coin on such a limited scope, whether it shifts or not.
You just need to put on the Gen4 mount. How you tell if it's a Gen4 mount you will see a hole at the front that's been filled in and at the back and underneath you will see a hole with a roll bin in them. The holes have springs and detents in them to hold zero and have more positives clicks of adjustment.