few year ago, was told verticele mounted crossbows failed comercially! anyway, I want to make some , after all, it is natural, and to shoot a bow verticely, so why do we turn it 90 degrees when mounted on a rifle stock???It would be easier to shoot between trees and brush instead of making sure it clears level with surroundings!
I have not found any data on said bows. I can think of no drawbacks

with this design, especially if I incoporate my idea of no paradox, since string would ride off the rifle stock
Hope I don't bore any of veterren readers/bow makers, my ideas may be old hat to them, been cussed and discussed many times!
Lrodshy