SAAMI has kept the pressure rating low just in case someone shoots a .323 diameter bullet out of an old .318 bore. The European industry standard is much more in line with the .308 Win or 30/06 I believe. You can shoot American made ammo without issue but you would be cutting the cartridge's performance off at the knees. If you compare the case head size to the 444 Marlin, which JD Jones uses for a lot of his cartridges, you'll realize you can load a little warmer than the 35K that the industry uses. I would not shoot the European factory loads in this barrel, I feel that they could cause a problem. In working with this cartridge and a 7mmJDJ#2, I found the CFE223 to provide higher velocities with no pressure indications. I think it might have something to with it's copper erasing additive slicking up the bore. I can't prove that, only a theory.