Brithunter: the business about the 'weaker old Mausers' is the US ammo makers liability excuse. Their concern was for the use of the .323 bore ammo in the older .318 bore - just a concern as none of the older .318s ever blew up (that I have rad about) although I think Thompson Whelan probably used a .318 bore with .323 ammo for accuracy 'testing' and subsequently put the death knell on the 8mm Mauser round in this country for nearly 60 years. As a result the 8mm mauser ammo made in this country is garbage - you would be better off with a 30-30 than to use US made 8mm ammo.
Hence, Sellier and Bellot (S&B) and PRVI. If you are going to shoot a European caliber, then shoot European made ammo in it. S&B, Norma and Fiochhi are all loaded to original Eurpoean specifications (pressures, velocity and bullet weight) and that ammo far outshines anything made in the US.
I also believe the 100'/sec increase you can obtain from the Ackley Improved cartridges use US ammo specs as a base - hence (I like that word) a 100'/sec increase in 8mm velocities means a 100'/sec increase over the US made ammo, not the European made ammo, the question back atcha is 'why bother'
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Thsi also goes for the 8mm/06. I like the idea of a 8x63mm round (8mm/06) but load data is still pretty soft as, of course, you are using a older Mauser action for the cartridge. I wouldn't mind building a 8mm/06 that would put a 200 gn slug out the bbl at 2700 or 2800'/sec but you won't find load data for that in any US manual.......jmtcw.