The 682 frame is a large 12 gauge frame, but small gauge barrels are made for it. There is another smaller frame for 20 gauge and some 28 gauge barrels. There is another even smaller frame that is used for 28 and .410 and I don't think that any 20 gauge barrels fit it. To add to the confusion, there are two sizes of 682 frame, but the barrels from both sizes fit either size. They just stick out a bit when the big barrels go on the smaller frame. The same situation applies to 12 gauge frame stocks. They fit both frames but the big stock sticks out a bit on the smaller frame. No big deal. Model 686 and 680 12 gauge barrels will interchange (with minor fitting) on 12 gauge 682 frames. I believe that Rich Cole may explain some of this on his website.
