This is how I've had it explained to me:
Self openers open on their own before and after the gun has been fired - self-opening Hollands, Purdeys on the Beesley-patent, & Atkin Spring Openers fall into this category.
Easy openers are assisted in opening only before, or after, they've been fired, not both before and after. Even then, they usually will not open on their own. Most Boss sidelocks with Robertson ejectors are like this, and I think Lancaster 12/20s and Churchill's built on the Baker patent are too (before). I think the wristbreakers are only assisted after firing (BTW: I think this may be another of Beesley's patents).
Boss did make true self openers from about 1932 - 1938. They're pretty rare. Most of the time, Bosses described as easy openers or self openers are just regular Boss sidelocks equipped with Robertson-patent ejectorwork. I don't know if Boss ever described these guns as easy or self openers.
OWD
