Peter I was not talking about Rigby loading as much as looking at what factory cartridges were doing in my rifle. I had origional Kynoch and RWS cartridges( still have some of the Kynoch left but I except the RWS as a modern loading ) that I shot for comparative testing when i was developing loads and the Kynoch ran at 2192 and the RWS ran at 2315and even if we only look at the Kynch load it is still a bit above the 1950fps that Grandveneur quotes for the RWS load. I agree that modern powders and bullets give some of our older cartridges a performance increase but I would still hesitate to recomend the 10.75x68 to be used where one might have comfortably used a 404 Jeffery except in ideal circumstances and that is not always the case is it.
As regards the 30-06 with the light magnum loading and it bridging toward the 300 mag would it not hold true that the same technology and subsequent powder developement take the 300 Mag that much further ahead and maintain the performance disparity. This takes nothing away from the developement of better performance capability for the 10.75x68 and I would be interested, as I am sure will others,to see the data that you have for these new loads.

Von Gruff