I forgot that I actually had some info on this rifle from about 4 years ago when my uncle asked me to dig up some load data on it (he doesn't load, but was looking for data to give to someone to load for him).

"Rigby Single Square Bridge Mauser Sporter 350 Magnum (I think MFG in the early 1900s). #85078 on the barrel and chamber. #5078 on the bolt action lever . #78 on the safety lever. # 4905 on the trigger guard and chamber. Inscribed on the barrel is: John Rigby & Co. 4 . 3. Sackville. SE London. W."

Is there any kind of date or S/N decoder available for these rifles? It would be interesting to find out when it was made.