"I can only guess that an over standard bore, with gentle cone dimensions and minimal if any choke gets us a bit tamer recoil event at firing."
Larger bore equal more volume in the combustion chamber and larger wad base area. Payload acceleration is the product of pressure times wad base area. Bigger combustion chamber will, at some point, equal lower pressure. When the product of lower pressure times larger wad base area becomes less than standard bore pressure times standard bore wad base area, the acceleration will drop and so, likely, will recoil experienced either from total recoil (MV will probably drop) or from acceleration (maybe felt) recoil.
The gentle cone and choke may make a longer, flatter shot acceleration spike and might show up in acceleration (maybe felt) recoil. The cone and choke constrictions should cause an acceleration to the shot and gun during passage and a shooter sensitive to gun acceleration might sense this as felt recoil.
