"Prior to 1980 these rifles were made in Manchester, England and sold in the USA by Interarms located in Alexandria, VA.'
The actions were always made in Yugoslavia, where the last of the military Model 98 Mausers (Model 48) were made and where the tooling continued to be used for the Maxk-X series imported "everywhere" by Interarms.
Manchester was an intermediate depot for Sam Cummings nee-Interarms, used for a variety of his activities. One of those was to do enough work to rifles to then be able to legally (Under UK law) stamp "Manchester" on rifles to give a "Tinge of England" on them to increase their acceptability for sale. "Churchill Mausers" maked "Churchill, Manchester" were the most obvious recipients of this sales tactic. I've got one in .375 H&H and it's a wonderful rifle. It's definately a Yugoslavian Mauser action though. Trust this, no Mauser has ever been machined out of a forging in England.