I use Unique in my reduced loads with 50 AE bullets in my 500 S&W loads. I think he meant Unique is not a powder for full power loads in the 500.
He (Ruggy) said it's "not a suitable powder for 500 S&W".
Lyman's reduced loads using Unique do go as high as 48K psi, the same as with slower/magnum powders.
By my calculations, an accidental double charge of their max. load of Unique would just overflow an empty case (104%). Still worth double checking the case before seating a bullet in reduced loads using fast/medium powders.
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