Brian, Grade 00 shotguns were first produced in 1898. In the patent dates you gave, the first one should be Mar. 20,'83. Since you serial number isn't listed, maybe the records were lost, you can go by a few things to get it close. One would be that the first patent date after 17 years no longer applies (1900). Patent object can now be made by anyone unless patent is applied for again. Second is that all numbers grades were changed to noun grades starting in 1913. So in looking at your serial numbers, the closest next serial numbers were 100000 in 1899, so I would guess yours around his time.