Round knob refers to the pistol grip of the buttstock. The wood can be shaped with a round knob, or a flat knob which is abreviated RK or FK. Long tang is the top tang of the breech block frame which is the metal that comes down the top of the buttstock and screws into the wood. Usually it is 1/2" wide and about 4"-5" long. Some Superposed guns have a short tang which is about 2" shorter. Typically a round knob Superposed with a long tang is more desireable than the flat knob or short tang.
Yes
1923 - 1966 had round knobs as standard stocks 1967 and up had flat pistol grips auto5man my browning a-5 made in 1988 in liege belgium has the roung knob stock, and i know it has never been changed. I ask the question " did browning offer both round knobs and pistol grips from 1067 on?"
The value of your Browning Sweet Sixteen auto-5 shotgun round knob can not be determined without you giving a detailed description of the shotguns overall condition including the condition of the bore.
Year.
Round knob pistol grip.
50-500 usd
This was made in 1958 if it has a round knob pistol grip. It is entirely possible that the gun was made in 1968 if it has a flat knob pistol grip.
1932, 100-1000 usd
50-500 USD or so
300 or so
your Browning superposed grade I lightning will bring between 750-1.300 dollars for a shotgun showing between 60%-90% of its original condition and a good set of bores.You may add 20-25% on top of the prices quoted if your shotgun has a round knob at the bottom of the pistol grip and a long tang stock variation(pre-1966 manufacture).The serial number that you provided,indicates that your superposed was made in the year 1937.
50-350 usd