Dtchman is right about the barrel fitting. My 2 groove RA barrel is done the same way. I have been told this is due to the '03 barrel not having enough metal in the shoulder. They do not fit 98 Mausers properly, as the barrel should bear both internally and externally on the receiver. The USGI barrel CAN'T do it. This is the reason why so few Mausers are found with 2 groove barrels. Many gunsmiths will not mount them. As best as I can figure, my Chilean Mauser has its 2 groove barrel bearing internally, this is the best solution to a poor decision. Does anybody know when Chileicon got its hands on 2 groove barrels?