smlekid,
That's a good question...if you have an LC Smith for example, there were several systems used. How would someone tell if they had Hurst & Schultz ejectors, Rosenberg & Schultz, or Lewis ejectors? (there's probably be more).
A friend and I had theorized that...if your selling a Smith with ejectors, wouldn't it be nice to know if your gun is the only known one with Hurst ejectors BEFORE you sell it?
We began photographing dozens of ejector mechamisms and single trigger systems in order to chronicle the evolution of American made guns. Unfortunately, the resident bum scoop mill from this BBS system brought about the demise of the collaberation and now everyone must do without that reference book.
I hope that in the future someone else will take up that project and publish a badly needed book.