mickey, the barrel channel looks as if it was rebarrelled at some time? looking at the lines of this gun i think it may have been built in the 60s, mike schwandt has one in 7x61 SH for sale that has the same look it was owned by ken waters who wrote for rifle magazine
your gun is most likely built of a military mauser, as oberndorfs were not availiable later i would contact paul roberts at jeffery rifles and ask for some info ,dont bother with rigbys of cali........nice gun ...paul