A.H. Fox Gun Co. Sterlingworth "pin-guns" with ejectors are not too common. The 12-gauge Sterlingworth serial numbers started at 50000 with The Sterlingworth Co. guns in 1910. The Sterlingworth was included in the 1911 A.H. Fox Gun Co. catalog and they transition to being marked Made By A.H. Fox Gun Co. in the 53xxx range. All the ejector guns I've recorded are 589xx and above. The transition to the smooth hinge pin is in the high 61xxx/low 62xxx range.
You might want to check things out at the A.H. Fox Collectors web site --
https://www.foxcollectors.com/
