I've been on about this for a year or more. I think I mentioned Prems in a PM to Simon.
Everyone raves about how the JSB's are used by most of the top target guys. Yet the variation is enormous and the game of finding a 'good' batch is tiresome.
The Prems always seem to be slated. They were the target pellet years ago. They always seem well made with so few rejects ( damaged ). They are big so they are tight in most barrels and they do steal power ( up to 1fp ). When you put them through the BIC there always seems to be 2 sizes.
In my S10 they are the only light pellet that groups well, and they group really well. In my 77s they also group really well. No messing about, like with the JSB's, finding a great Die that groups superb, but several Dies that are poor.
Paul told me that he used Prems and it's quite well documented that he used to split them into sizes and then check what size suited his 77. He then used an adjustable sizer ( I presume like the T R Robb style ) to resize all the oversize ones to the size that his 77 shot best.
I reckon if they shoot well in your barrel then doing it that way gives you an opportunity to just keep buying the same pellet and size the larger ones down and you will just keep getting reliable pellets to shoot.
The JSB thing is just turning into a farce.