Winchester Model 21 Frame Size

[Phil C]

Bill, sorry for the confusion. The same as a 10 gauge Parker that had a set of 12 gauge barrels that were fit to the gun. 16 gauge after market barrels that are fit up to 20 gauges I believe. although possibly the barrels may have been produced to meet the firing pin measurement of a 20, not sure. A LC Smith 20 Gauge with a set of 28 gauge barrels I had fit up by buck Hamlin for my Crown grade 20.
My 10 gauge worked just fine with the 12 barrels but the couture was not perfect. The firing pins stuck the 12 gauge shells slightly off center but worked perfect.

There was actually 3 Frame sizes for the 21's but surprisingly very little difference between the frame's overall dimension's.

I can understand how a 12 frame would not work with a 20 gauge set of barrels as the distance between the striker holes on a 12 gauge is 1.14 and a 20 gauge is 1.02. The 16 gauge is much closer I believe 1.08.