Gentlemen,
I am no expert on Model 12's but I have several, including a 16ga. serial#477XXX (mfg. 1927), 26" NICKEL STEEL barrel w/cyl bore. Careful examination of the back side of the slide bar reveals "16-20" stamped on it. A newer example 16ga. Model 12 in my posession, serial #716XXX (mfg. 1936), 28" WINCHESTER PROOF STEEL barrel w/mod choke does not have this mark on the slide bar. Right or wrong, I always been of the opinion that the 16ga. Model 12 was built on the 20ga. frame.
Gerry
