For this week’s Gunfight, it’s o/u vs. side-by-side as two heavyweight classics square off. These guns are heavyweights both in reputation and in heft and stoutness, as anyone who’s ever picked up either gun can attest. The Browning Superposed was John Browning’s last design. He was actually working on the gun when he died in 1926 and his son, Val, finished the job. The Model 21 was the brainchild of Winchester’s John Olin. It debuted in 1931. Olin built the gun to be strong, and to promote it, he devised a proof-load torture test pitting the Model 21 against doubles from around the world. Each gun was fed over-pressure proof loads until it failed. The 21 beat them all, digesting 2,000 proof loads without a hitch.