A few years ago in a rather upscale gunshop I found a Thomas Bland 2.5" 20 ga SxS that tipped the scales at no more than 5 lbs, a well balanced "wand" with 28" or 30" barrels that moved and swung with the grace few modern, production-line guns could even come close to matching. One explanation, of course, was the pedigree. But as far as the weight per se was concerned, I couldn't help but notice how slender the receiver was when compared with "modern" 3" guns. In comparison with an SKB, Winchester Model 21 or even a Merkel 20 ga SxS, the Bland receiver was much trimmer, which translated into a much lighter, better proportioned gun.
Several years later, I bought a 2.5" 20 ga Cogswell & Harrison side lever single barrel "hammer gun" with an English stock that weighed all of 3.5 lbs--an Everyman's gun in every way but remarkably light and well-proportioned.
A few days ago I had the opportunity to purchase a 20 ga Model 23 Winchester that must weigh at least 6.5 lbs and has 3" chambers. Like the modern Merkel and the Win Model 21, this gun is nearly as wide across the bbl flats as are the OD of the barrels themselves, which naturally translates into a heavier gun.
Considering that, with a little assiduous searching, one can find a decent 2.75" 12 ga double weighing 6.5 lbs or thereabouts, it makes you wonder what the price of the 3" 20 ga has been. If we (meaning we Americans, I guess) weren't so wrapped up in having an all-around gun, capable of handling everything from woodcock to late-season wild pheasants to maybe ducks over decoys, maybe our treks afield would be a lot less "weighed down", a consideration that becomes more important by the year in my senior dotage!

Granby