The 1200s and 1300s are different animals.
Other than "cosmetics", in what significant
way(s) do the Winchester Models 1200 and 1300 shotguns differ? Author Don Zutz, in his book Modern Waterfowl Guns & Gunning, described the Model 1300 as being a "revamped" Model 1200, saying, "...Both guns have high-strength aluminum receivers, cast and stamped parts, and mass-production assembly..."
In his book, The American Shotgun, author David F. Butler reported that the Model 1200 endured extensive 1,000, 5,000 and 10,000 round endurance test cycles during its development, "...the whole cycle (being) repeated again and again until the mechanism had been so refined that it could stand long endurance tests without breakage..." Mr. Butler concluded "...This meant that many components within the Model 1200 were stronger than they had to be for a slide-action shotgun, but the design team felt that these decisions would result in a smooth-working, long-lived shotgun..."