What we know:
The Winchester Model 21 went into production in 1929, but was not listed on the Winchester price list until 1931. In 1933 the Model 21 Skeet Gun, available in Standard, Tournament, Trap grades was introduced.
1933
Hunting & Fishing
Bro. Walt's engineering diagram is dated 1934.
Crossman wrote in 1936 that Ithaca invented the 'bell' choke "years ago".
He obituary in
The American Rifleman makes no mention of his ever being an Ithaca (or any other maker) representative
http://smg.photobucket.com/user/Ansleyone/media/ECCrossmanobit.jpg.html I'll choose to believe him.
