In Greener's 9th Edition (only Greener book I have) he seems to describe the "Rationale" stock as pertaining more to the comb line than the grip. The comb was arched & designed to serve much the same purpose as a Monte Carlo.
The Germans also made some guns having this arched comb, I forget their name for it, but it more or less interprets to SwineBack.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra