Forsyth spoke of rifling as being a hill the ball or bullet had to climb, thus increasing recoil and reducing velocity over a smoothbore of identical gauge.

We tried the test as I noted above, but the subjective recoil test phase was not possible due to different ergonomics & weight of the 20 bore guns used. There was literally no difference in velocity. Thus, from the test, we felt recoil was most likely similar as well- but not tested.

I think Mike's 8 bore would have given a more accurate representation on both aspects & should be believed. It is the perfect test vehicle.