I have just taken custodianship of a 275 Rigby - its got the Pall Mall address so late 1960's. Built on a CRF Mauser action, but not a military one - solid side wall, and magazine / trigger guard looks to be a casting rather than machined from solid. What actions where Rigby using in those days - Parker Hale / Brno's or proper mausers?. Trigger looks like a Timney with side safety.