Sorry Bill, I can't answer your question as such, but can tell you they list RS 50 as their fastest powder recommended for use with the 243.
There are more recipes in their reloading data handbook but the fastest powder being used is RS52 and these are loads from homeloaders.
It would appear that they are getting most of their data this way, hopefully a new load data handbook will be out soon (mines from February 2015).
Regards,
Mark