I did not know that about shotgun rounds. Truthfully, I just held an unfired S&B up next to a Federal to compare length.
As an aside, a fraternity brother of mine had an old 16-gauge Auto-5 chambered for 2 9/16" or something. He had to open the crimps on 2 3/4" shells, trim off 3/16" with an exacto knife, fold the crimp back down and drip candle wax on it. Worked pretty well.