I've been using Claybuster wads for 15 years or so, and have never heard such a thing. Some of the first wads I used were CB3118-12A bought at a garage sale, and was told they were 10+ years old at the time. I used those wads for some mighty fine buckbuster slug loads. I'm not saying it wasn't true way back when they started, but it surely has not been the norm for a long, long time.