Probably you alls best bet for any of these Fox questions is to take them to the A.H. Fox Collectors Association, Inc.'s web site --
http://foxcollectors.com/My%20Forum/php ... 5b3c51cbe1
The A.H. Fox Gun Co. was founded in 1905. The Sterlingworth was introduced in 1910.
Sterlingworth -- When Ansley H. Fox, was forced to add a lower priced gun to his line of graded Ansley H. Fox guns, in 1910, he didn't want to detract from the A.H. Fox Gun Co. name, so they dummied up "The Sterlingworth Company." The first year's guns, beginning with serial number 50,000, were marked as being "Made By The Sterlingworth Company, Philadelphia, U.S.A." Actually the first few hundred were marked "Wayne Junction" instead of Philadelphia. They even produced a separate The Sterlingworth Gun Co. catalogue for 1910. These guns were built under the same patents as the graded Ansley H. Fox guns. The main moneysaving features were an American Black Walnut (Juglans *****) stock as opposed to the more costly European thin shell walnut (Juglans regia) stocks on the graded guns, and the "Sterlingworth Fluid Steel" barrels instead of Krupp Fluid Steel barrels. Workmanship on these early Sterlingworths was generally excellent, better than graded guns from the 1920's and 30's. The early "The Sterlingworth Company" guns had a rounded front for the side panel of the frames. According to my list of observed specimens that was changed to the same pointed profile as the graded guns by #51,301.
In 1911 this field grade gun was added to the A.H. Fox Gun Co. catalogue as the Model 1911. "Model 1911" is stamped in the forearm iron. (A very few graded guns made about this time are stamped Model 1910) The lowest Model 1911 serial number I've recorded is #53,140. All of these early Sterlingworths had a recessed hinge-pin head like Parkers, or Ansley's earlier guns made in Baltimore and the Philadelphia Arms Company A.H. Fox gun. The highest "pin gun" Sterlingworth serial number I've recorded is # 62,244. After that Sterlingworth hinge-pins are dressed smooth like the graded guns. When the small-bores (16- and 20-gauge) were added to the Ansley H. Fox line they were briefly referred to in some flyers as the Model 1912, but I've never seen one so stamped. Graded 20-gauge guns have serial numbers beginning with 200,000 and 20-gauge Sterlingworths 250,000. Graded 16-gauge guns have serial numbers beginning with 300,000 and 16-gauge Sterlingworths 350,000.
Most of the Philadelphia produced S-worths had the word "Sterlingworth" roll stamped on each side of the frame. After production moved to Utica, Savage started using a "Fox-Sterlingworth" roll stamp.
When the Sterlingworth came out in 1910 it had a price of $25. That climbed to $55 by 1919. A.H. Fox Gun Co. reduced the price to $48 in 1922 and again to $36.50 in 1926. Workmanship of course declined. Savage kept the $36.50 price until June 1932 when they upped it to $39.50. On February 10, 1936, they upped the price again to $42.85 (the digits 2 and 8 are transposed in McIntosh's book). On February 1, 1938, Savage tried a price cut and dropped it to $35. February 1, 1939, they upped the price to $44.75. January 2, 1940, up again to $48.50. January 2, 1941, up to $52.65 and June 16 up again to $56.50. January 2, 1942, up again to $64.95.
For $40 Graded or $30 Sterlingworth (last prices I've seen quoted) you can get a factory letter on most any Ansley H. Fox shotgun (Philadelphia or Utica) from Mr. John T. Callahan, 53 Old Quarry Road, Westfield, MA 01085. The information exists on the factory work-order cards, probably 85+% of which still exist. Send him the complete serial number and a check, and he can do the rest. That would tell you the specifications of the gun when it left the factory.
There were more 12-gauge Sterlingworths made than any other Fox double (some 110,000, the great majority with 30- or 28-inch barrels), so unless in exceptionally high condition or with features such as automatic ejectors or factory original 26- or 32-inch barrels, they are about an $800 gun. It is impossible to truly evaluate a gun with out having it in hand, but average 12-gauge Sterlingworths are about $800 guns.