Once again I appreciate all the feedback - so many thanks.
The newer dumpier JSB's are straightforward EXACTS not premium. I've purchased 4 sleeves (40 tins) of them and taking random samples they all look the same. Just worried that they are not as 'efficient' as the older longer pellets as they fly much slower (less power).
Strange - not sure what to do when I soon run out of my lovely old batch, maybe recalibrate our 2 FT PCP and 2 springers rifles?, will be like starting all over again.