I think the old 20s were made on a 12 gauge frame....along with the 16s. I have one of the newer 20s (about 10 years old) and a 12 made in the days of chrome lifters and impressed checkering. They are both quality shotguns, the 12 is a bit smoother...but it's been fired a lot more. The newer Wingmaster is no slouch. I replaced the shell follower with an aftermarket aluminum follower, just cause I didn't like the plastic. With it had a shiny, reflective chrome lifter smile. But it's well built and pretty darn smooth.