Maybe yes, maybe no- I went to my signed copy of Steve Bodio's book "Good Guns Again"--1994-Wilderness Adventure Press: ISBN no.: 1-885106-o6-8.. pages 42 & 43--In his discussion of this model, Steve wrote: The 16 is exceptionally well-balanced, and 3-inch 20's on the same frames-- etc.. Not 100% proof, but possibly enough for a discussion over "sundowners" perhaps. As I do not own, nor plan to purchase a M21 in either 16 pr 20 gauge, it is a moot point.
One reason I like Bodio's book is that in this same chapter he goes on to praise my favorite, my "go-to" shotgun- the "Perfect Repeater" On page 44, he even quoted Mr. Geoffrey Boothroyd, a noted British gun writer for "Shooting Times & Country" magazine-
"The Winchester Model 12, for example, cannot be faulted in its styling, whereas the much vaunted Winchester Model 21 double is, in my eyes-- truly ugly--
I have to look for my O'Connor book, also my copy of Gene Hill's "Shotgunner's Notebook" and see what they may have said about the M21's and various frames. Somewhere I recall reading that the M21 had 2 frames at first- 1 for the 12, 1 for the 16 and 20- they later increased that to 4, adding one for the 12 with a Ventilated rib, and one for the 16 and 20 with that same optional feature-- My Dad's old 12 field grade has 3" chambers, as marked on the barrel breech, but is NOT a DUCK model- and the frame mikes out the same as a friend's 12 M21 skeet grade- FWIW- both are guns are pre-Custom shop era, with the reinforcing bosses on the receiver sides--RWTF
