Model 21s are not inherently extremely heavy. I have owned 28" barrel 20 gauges as light as six pounds, four ounces. A friend built a 28" 20 gauge at six pounds even. Trimly stocked 30" 12 gauges can be built at seven and a quarter pounds or less. Postwar field grade 12 gauges are a bit clubby, but they have way more wood than they need to be properly stocked.