Because the original shipping records record only 44 examples of the 20-gauge Smith "R" framed model as having ever been built. Obviously all of these recorded examples would have been produced after 1917-18 when gun frame size was first recorded within the ledgers; but who knows how many examples may have been built between 1907 (1st year of the 20-bore) and 1917? I suspect a few. The real odd thing is that no examples seem to ever surface; especially given that Smith guns/models with much smaller production numbers have.