He also states that in 1947 American manufacturers adopted the crimp turnover and at that time the standard length of the case was increased to two and three-quarter inches
Two Piper, my post was in response to the above quote. American gun and ammo makers had arrived at the 2 3/4" case length (and chamber length) as standard for 12-16-20ga over a decade prior to that, although there were a few holdouts (like Hunter, sticking with the short 16). And of course the old, short factory shells remained readily available for some time even after 2 3/4 became "standard" in the States.
