AH Fox 10 ga?

[Silvers]

EDITED SEVERAL TIMES FOR CLARITY

The math doesn't seem to add up here. Interesting that your friend measured with a metric caliper or whatever. If the chamber measures 19.7mm (I assume at its smaller front end), that would be 19.7/25.4 = .776" which is slightly smaller than the accepted minimum 12 gauge chamber dimension (.798" or about 20.3mm). A 10 gauge chamber would measure about .841" diameter (21.4mm) at its forward end.

On the other hand 19.7mm is on size for the nominal 10 gauge bore diameter = .775"

I wondered if someone could have rechambered a regular 12 gauge Sterlingworth to 10 gauge, 2-7/8" shell, and use a very long tapered forcing cone to transition the shot charge into the regular 12 gauge bore. Of course if that were even possible on a 12 gauge Fox it would result in a VERY UNSAFE MODIFICATION due to thin chamber and barrel walls over the forcing cone. But after thinking about this and looking at a barrel on the bench I determined that the rims of 12 gauge shells (.885" diameter) just barely miss the sides of the top barrel extension on a Fox, and there isn't any room for the rims of larger 10 gauge shells (.932" diameter). If rechambering to 10 gauge were attempted on a regular 12 gauge Sterlingworth, the the barrel extension would have to be partially milled away on its sides. At a minimum the width of the barrel extension and its locking slot would be reduced by about 1/4. THEREFORE, rechambering a regular 12 gauge Sterlingworth to 10 gauge as theorized here just doesn't seem practical.

IMO about the only possibilities for a 10 gauge prototype Sterlingworth is if Fox forged and machined a special larger frame, or as described here by Eightbore, if the hammer tip centers & height and frame geometry were changed. I highly doubt that Fox or Savage did that.

Now, if you have a Sterlingworth that measures about 2.500" across the breech balls, accepts 10 gauge 2-7/8" shells, has a bore of about .775", and weighs over 9 pounds or so - I and others would surely like to see it! Silvers

[eightbore]

To determine whether a Fox can be barrelled to ten gauge, the only limiting factors are the distance between firing pin centers and the distance from the firing pin center to the water table. I owned a very small frame Lindner Daly that had a professionally installed set of pigeon barrels that had outsized breeches that extended beyond the breech balls. As long as the base of the shell itself is contained within the breech balls, the outer chamber area of the barrels can be unsupported. I know this is an unorthodox method of shotgun building, but my old Lindner Daly recently changed hands again for around 8 grand or maybe a little more. This would be an interesting project for a talented Fox gunsmith.

[MarinePMI]

I'm hoping to get a look at it physically myself soon, as I'm not sure what to think without measuring it myself.

I'll let you guys know what I find out (hopefully before the Xmas break)...

[Researcher]

By the time the Sterlingworth came along in 1910, the 10-gauge market was so small that Baker, Ithaca, Lefever, L.C. Smith and Parker had it more then covered. Parker Bros. 10-gauge production from 1911 to WW-II was 422 guns. Baker was out of the 10-gauge business by 1915, while both Lefever and Hunter Arms were out of the 10-gauge business by 1920. Even Ithaca, actively promoting 10-gauges, only managed to market 887 of their vaunted Magnum-Tens during their production run from 1932 to 42. Fox getting into the 10-gauge market would be a non-starter.