Transition to 2 3/4

[gman]

Like many others I spend a lot of time looking, studying, and occasionally buying parkers on the internet or whenever at a shop or a show. Many guns listed do not share chamber length in their write ups and I think many do not know what the specs are. I generally assume before I inquire further that most of the early century guns in 12, 16 and 20 are 2 1/2". Occasionally some point out 2 3/4 and the convenience of modern length shells. Although there is no real substitute for a chamber measurement I was curious if there is a time table as to when the 2 3/4 where introduced and the 2 1/2 faded out of production?
Thanks and great web site.
Eric