The Winchester lever shotguns are pretty much of an anomaly. The first model, 1887, was in 10 or 12 gauge, while the later, 1901, was 10 only. This would have been contrary to the transition generally from the 10 being as common as the 12 to becoming a relatively rare bird. The 1901 was the last repeating shotgun in 10 gauge until I believe Ithaca brought out a semi-automatic.