I had the same problem with a Tasco scope once on a .223! It happened once because I learned to buy better scopes. My first recommendation is Leupold. Even their rifleman line is good and their top of the line is very good. Recently, I got talked into a Burris because the store owner claimed they were just as good as Leupold but less costly. At the range with Leupold and Burris side by side, the Leupold was clearer. I sold the Burris and bought a Leupold replacement. I have no connection with Leupold and I don't sell them, I am just one of the many very satisfied customers that has bought their scopes for more than 20 years now. Other brands that are tops, Leica, Swarovski, Schmidt and Bender, Zeiss and I've been impressed by some of the upper end Nikons. There are others that are good but many of those others also make cheap scopes so I don't recommend them unless a specific model is mentioned. Probably more than you wanted to know.
