The history and science of short chambers

[J.B. Books]

Originally Posted by Arthur Shaffer

Keep in mind that at the time of the work there were no plastic wads or shot cups. The extended shell basically provided a soft instead of a metal forcing cone. This is the very reason plastic wads and shot cups were developed, proving the work's validity. For the vast majoroity of shooters now, it is no longer an issue.

I would say plastic wads were developed to make the mass production of shotgun ammunition easier. My point in sharing this is to demonstrate short chambers did not result from changes in ammunition length, it was deliberately done for better performance.