Bored sitting around waiting to go to our friends for Thanksgiving dinner I weighed some Model 31 barrels, all three 30-inch full.

Vent rib from 1949 Model 31-TC -- 2 pounds 2.8 ounces

Solid rib from 1947 Model 31L -- 2 pounds 5.5 ounces

Plain barrel from 1947 Model 31A -- 1 pound 15.3 ounces.