Discussed this rifle years ago with both Lud Olson and the then owner. I don't think it being a "Drückjagdbüchse", because of the ds trigger. Further, such specialized short range, driven game rifles appeared in the 1970s only, with the increase of wild boar numbers in Germany. The Schnabel foreend tip was common on all B halfstocks from 1912 on. What is more unusual is the checkered foreend. This was an extra-cost factory option from the 1930s, but not often seen. But it was common on stocks made by Walter Roell post-war. We came up with several possibilities:
Even pre-war some people preferred carbine length barrels, but mistrusted the fullstock Stutzen foreend out of fear for wood warping. So some half-stock, carbine length rifles were always availble on special order. My 1920s Mannlicher-Schoenauer M1910 is of the same configuration, 20" barrel with "rifle" half length foreend. Steyr now calls this configuration a "Goiserer". So maybe it`s a special order item, made for a hunter who preferred a short rifle, but had no use for a sling or swivels.
The other, more likely to me possibility: The rifle left the factory as an type S Stutzen. Not a type M because of the round bolt handle. In the 1945 disarmament the original stock was broken off at the hand by a GI. (I myself inherited a gun with this damage) Later it was restocked with a B stock by Walter Roell. WR, as the last master of the Mauser sporting rifle department, had "inherited" many left over parts and had the original Mauser numbering stamps. Common with German military armorers he numbered all replacement parts to the original serial number.
Or, Walter Roell had inherited the left over 1941 proofed S carbine barreled action and completed it with an equally left over B stock for an allied officer in 45. Roell's early post-surrender work is of course hardly distinguishable from the one he did at the Mauser factory a few months before.