40 plus years ago, when I was shooting Skeet seriously, 26" was the norm and 28" was considered long barrels. Four barrel sets were the ultimate and sets of pumps or semi autos were what poor people had to shoot. Then along came Claude Purbaugh and later Jess Briley, Skeet Masters and Kolar tubes. Combined they changes Skeet for ever. Tighter choke and heavy guns became the norm. We accepted that barrel heavy guns were better because we did not stop our swing. We accepted that 28" was better than 26", in turn we accepted that 30" was better than 28" because the longer sighting plane and more forward weight was smoother. Later it became 32" and even 34" made a decent following. It is the Indian not the bow or the arrow.
Truth is that if you mount the gun and look right down the barrels the length becomes impossible to know. I perceive that same lead for short or long barrels. It all looks like it is half an inch long to me. MOI is another matter but you could get the same MOI by changing the weight distribution so that 26" barrels weighted the same as 32" barrels. It would cost money but it can be done if you desire. Most of my longer barreled guns I shoot better because they are heavier and my swing is smoother.
What really has changed is the chokes we use and the quality of our ammo, especially in the smaller gauges. Today's ammo is vastly better than anything we had back then. If I had today's Winchester AAHS or the Remington equivalent several of my 395-397 would have been 399-400's unless that lump in my through caused me to choke.
