Any chance the Schweinsrcken(Hog back) is related to the Schiestock usw. term in Gebrauchsmuster Nummer 134556 was from 3.03.1900?
No. DRGM # 134556 was for a Schiestock = shooting stick = cane gun, a walking stick with a built-in gun, peep sight and safety arrangement by a turning ring that blocked both the folding trigger, the striker and sight. The Word "Stock" is a stick. "Stock" in German is never used for a gunstock. A gunstock is a "Schaft" in German, a word of the same origin as the old English "shaft", the wooden handle of a spear.
DRPatent # 123902 (1901) covered Krieghoff's "scientific" procedure to calculate the "ideal" gunstock dimensions from body measurements of the customer, calculating from height, arm length, cheekbone, shoulder, neck, chest, shoulder to eye dimensions. A hogback stock is not mentioned here, though it may be a result of such calculations.
BTW I too believe in a postwar, 1960-70s, restocking job because of the shape of that hogback stock and that silly white-line spacer under the pistol grip cap. Such useless spacers became fashionable in Germany in the late 1960s only, together with "Scottish" skip-line checkering. These adornments were influenced by the "California style" Weatherby stocks then made by Sauer & Sohn, Eckernfrde. It was the same time when cars had lots of useless chrome, shark fins and white-sided tires.
