Well of course the Standing Breech "CAN" be cut 90 to the water table. The barrels will ordinarily have additional metal on their bottom which is cut "Flat" to mate with the action flats. I have never actually measured to see if it was or not but this could well be cut parallel with the bore axis. What is ordinarily done & what "Can" be done is often entirely different things.
Wonko;
The simple act of imagining a line perpendicular to the line joining the center of rotation to the juncture of the table & standing breech was not intended in any way to show how a double gun was constructed, but simply was to show that one so constructed "Would open". "IF" you would like to show your Superior Intelligence then Prove Me Wrong otherwise as far as I am concerned you can Cram It.
This whole thread generated from the misunderstanding that as the hinge on an ordinary SxS double is below any point on the breech of the barrels those points are upon opening moving Both up & forward. That point of tangency to the circle of rotation taken at the lowest point of the parts in rotation then determines the Maximum angle the breech could be cut to & still be operable. Certainly that angle would never be cut to such a great extent, that was not the point.
