I wouldn't be surprised if the Super-Fox in question is one that's currently on one of the on line auction sites. Just looking at the pics there, I don't see the proprietary Fox 3 IN chamber stamp, and without doing a record card check a reasonable assumption is, that S-F was/is chambered for 2-3/4" shells. Super-Fox chambers were "cut tight" to center the shells and allow a repeatable transition of the shot and wads into the forcing cone and bore. Using a standard chamber gauge, these S-F 2-3/4" chambers often appear to measure about 2-1/2". Personally I've never had good luck using the machinist scale method on Supers. It's very hard for me to feel the transition from the front of the chamber into the forcing cone. Others have reported it's worked for them, so what can I say?
I'm particulary interested in Supers with 3-inch chambers and have done a bunch of cerrosafe casting of said chambers on original guns. That led me to getting a some special gauges made to match the Fox chamber diameters and taper - which were not industry standard at the time. I usually have these gauges with me at shoots and am more than happy to measure Supers with 3-inch chambers to confirm or deny they are factory. I've seen many factory 2-3/4 and even 3 IN Super-Foxes that were redone with modern type 3-inch chamber reamers and they will measure overdiameter as compared with the special Super-Fox factory 3 IN chamber. Why rechamber a Fox factory 3 IN chamber? To make it easier to load with some 3-inch paper shells back in the day. To complicate things, most but not all 3-inch Fox factory chambered Supers are stamped 3 IN. In fact I measured two last year at Hausmanns that were not stamped 3 IN but were absolutely original-chambered. But two months before I measured two other Supers at Chuck's shoot at Blue Ridge that had more-less modern "sloppy" 3-inch chambers. Sometimes it's better not to know. Sorry for the long diatribe.
PS: I don't charge a fee to measure 3 IN Supers with my gauges but you will owe me a cigar or soft drink, etc.
Frank
Threaded Mode