Circa 1964 Tom Burgess (who lamentably recently left us) did the metalwork for three rimless cartridge HiWalls, I own one, a 6.5'06 stocked by Kennedy, the second was a .244 Remington and the third was a 7mm Remington Magnum where Mr. Burgess opened up the receiver ring for a larger barrel shank. This is all as per a telephone conversation with Mr. Burgess several years ago.