A shell should "Never Ever" be fired in a chamber having a step rather than a cone if its fired length is greater than the length of the chamber. Shells which upon opening lap into a "normal" cone (Neither ultra short/stepped/lengthened) by 1/8"-3/16" have been successfully used with out ripping the ends from the hull or any other undue consequence for nigh onto a century. Accept it or not, but this is indeed verifiable fact, & was occurring PBB (Prior to the Birth of Bell).
He may well have brought this to a lot of folks attention, but it was established "Fact" long before he ever thought about it.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra