The present working theory is that 12-gauge frames with serial numbers from 1 to 3000 were made at or at least serial numbered for the original A.H. Fox Gun Co. factory at Wayne & Bristol Streets, 1905-06. At the end of 1906, the A.H. Fox Gun Co. moved into the factory at North 18th Street and Windrim Avenue that was built in late 1903 for the Philadelphia Arms Co.
From fifty plus years of observation it appears they skipped four thousand serial numbers and the next batch of 12-gauge frames were serial numbered from 7000 up. Some of those frame from 1 to 3000 were assembled into finished guns later at North 18th Street & Windrim Avenue. The very earliest guns from Wayne & Bristol Streets have only one patent date on the watertable --
104 A 04.jpg
Not too far into things they moved to a three patent date roll-stamp --
1331 02.jpg
And, here is an example of an early frame finished much later with a later patent date roll-stamp --
1515 01.jpg
The 1902 and 1904 patent dates were actually Philadelphia Arms Co. patents. Guess they figured that now they owned them they should stamp them on their guns whether they applied or not?!?
Only about ten production cards survive for graded 12-gauge Ansley H. Fox doubles below 9640 and they are primarily for salesman sample cut-aways. So, we are on our own for assessing guns below that serial number.