>>64280902
>know it was a Mauser Model 98 in 30-06, but what was the exact brand and make?
My best guess is it's an old German Mauser from either WW1 or WW2 that was originally chambered in 8mm Mauser, then brought to the states either by a soldier returning home or a company importing them for sale on the American milsurp market, which happened a lot during the 50's and 60's. There were a shit ton of military bolt actions from other countries brought into the states during that time, so they were inexpensive - but the ammo was often difficult to find. It was very common to re-chamber rifles from 8mm Mauser to 30-06, because it's a relatively easy thing to do and 30-06 is obviously ubiquitous in the States.
It was also very common in those days to "sporterize" milsurp rifles (picrel). This means cutting down the stock (or just replacing the stock), cutting down the barrel, and often changing the sights and caliber. Today we look down on this practice because it "destroys the historical value" of the rifle, but in those days these rifles were plentiful and cheap compared to commercially-produced hunting rifles, so nobody had an issue with sporterizing them.
Anyways, it's a sporterized Mauser 98. Nothing particularly special about it. There are some indications from the court filings that it was originally Robinson's grandfather's rifle, so a family heirloom of sorts.