If I remember correctly the gun Fergus reported on was a very early gun which essentially had "No Cone" but a step at chamber. It could have been cut with something like a 45° angle rather than being absolutely square, but this would still be essentially not a forcing cone as such. In such case the longer shell would indeed open into the "Bore" of the gun.
As to more Work producing more recoil, if one placed a fitted solid steel plug into the forcing cone which effectively blocked the bore & totally prevented the crimp even opening at all or any movement of the charge enough "Work" would be performed to "Rip Open" the chamber walls but no recoil would occur because nothing moved.
Anything which "Retards" the movement of the shot, friction etc, produces a "Forward" push on the gun equal to the retardation of the charge. This is the reason "Pressure" is not a factor in recoil formulas. Recoil is the result of the gun moving in an opposite direction to the charge.
One more time, Anything which "Retards" the movement of one "Retards" the opposite movement of the other. Mr Jim Legg's statement is absolutely true, any "Anecdota" statements notwithstanding. Any statement of increased recoil without accurate velocity checks is totally "Worthless"
