Lengthen chambers to 2 3/4" ??

[Andy]

I have a few questions and am not intending to hijack. Without having to pull out TPS, why were 2 5/8" chambers made for 2 3/4" shells? And while I use a brass gauge for chamber length from Ct. Shotgun, what is the most accurate way to measure it? If I see it land on "the lip" of chamber between 2 1/2" and 2 3/4" I just assume it's 2 5/8". We know what happens when we ASS U ME I've been told on here if they are Vulcan steel barrels and the gun is sound, low pressure 2 3/4" are fine and many people do.

EDIT: I read the other threads about fiber wads and paper shells and the chamber creating a better seal. So that's solved. The chamber length issue?