Jack O'Connor on chamber length

[Northwester]

About a week ago I picked up an old book titled "The Shotgun Book" written by the Jack O'Connor. Jack was the gun editor for Outdoor Life for about four decades or so. The book was copyrighted in 1949, with additional printing in 1955, 57, 58, 1960, 61, 62, 64, 65. I purchased the 1965 edition. On page 90 of the 1965 edition Jack talks about chamber lengths of US made shotguns. I would like to quote what Jack wrote in reference to chamber length. "Chambers in American 12-gauge barrels were standardized at 2 3/4 inches right after World War I. The 16-gauge chamber were standardized at 2 3/4 inches in 1929, the 20-gauge chamber at 2 3/4 inches in 1926. A 3-inch chamber became standard for the .410 in the early 1930's when Western and Winchester brought out the 3-inch .410 shell and a gun to shoot it. The 28-gauge was standardized at 2 3/4 inches before the last war." What do people think about that paragraph?

Of course, adoption of a new industry standard takes time as the manufacturers must tool up for the pending change(s). Therefore I would think that there was some change control document / drawing which was pushed down from engineering to the production floor. We all know that chamber length wasn't mentioned in the 1920's and most of the 1930's catalogs, so it's not immediately apparent when Fox started to comply. But at the same time we still have production cards for many serial numbers. Therefore is it a stretch to believe that somebody out there might have some engineering change control documents about chamber lengths?

[Researcher]

Cactus Jack was a great writer, but not a great student of historical facts.