Seems like the only shotguns on the market that move are 12 gauge? Why was 12 gauge so popular? I always wondered why it won out over the alternatives. Weren't there like 5 or 6 different size guns back in the older days?
16 and 20 gauges were popular back in the old days. My grandfather was a fan. I have no idea why... just know that he had them. One of the nicest shooting shoguns I ever owned was a 16 gauge Winchester Model 12 with a 26" skeet barrel and Simmons rib. It was great the first day of dove season. Of course, back then, Winchester scaled the receivers so that the 16 was slightly smaller than the 12 gauge version and the 20 gauge was scaled down accordingly, etc. That made them very handy and quick pointing. Just look at the size of the receiver on a Model 42 Winchester, which is basically a Model 12, but in .410 bore. It is even smaller still than the 16 or 20 gauge version. In short, what killed the 16 gauge was when the mfg decided to use their 12 gauge receivers for the 16 and when the 20 gauge mag came out. The added weight of the new guns, plus the 20 gauge's shot advantage took a toll on the 16.
I hunted up land birds with a 20 gauge when I was a kid, used the 12's for deer with slugs ... The 12 gauges got popular, bigger shells, more pellets less cripples ... WPT ... (YAC) ...
I've got so much of that stuff laying around I'll never shoot it all. My two new Belgian Browning A-5's (Sweet 16 and 20 ga.) are begging for some use. I might be forced to shoot at least one of 'em this year on some stocked birds!