(Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings, the .260 Remington case can handle up to  piezo pressure. In C.I.P.
The decisions made by (CIP Permanent International Commission for the Testing of Portable Firearms) indicate that the .260 Remington cartridge can endure pressures as high as piezo. According to C.I.P.