rigby mauser, i looks like the 303.setup for a scope ,the handle shoulder looks to be trimmed and the bolt shroud color as we can see is not original ,did it have a sidemount at one time?
i know that the 303. rigby is a rare gun, i have 1 example (not a takedown), i just think that a lot of nice rifles seem to be coming up for sale monte mandarino who had that osa rifle has been coming up with some good stuff, and right now if it hasnt been sold ,he has a TYPE A 7X57 that is real nice

huvius ,that oberndorf buttpad was probably setup for a women same with the osa rifle if you notice ...paul