Guys, the specific point of the post was about forcing cones. I believe that a lengthened forcing cone will reduce recoil. How much, who knows.
It seems to me that in a short forcing cone (more acute angle), the hesitation of the wad and shot as it is abruptly forced into the barrel causes a spike in pressure, hence recoil. Alleviating the angle on the forcing cone to one that is three inches long and much slighter angle would stretch the recoil impulse over a longer period (as opposed to the spike),hence softer recoil.