Assuming that's the serial number, I asked Grok:
The shotgun with serial number 12100 from William Powell & Son (Birmingham, UK) dates to approximately 1908–1912.
William Powell sequentially numbered their guns starting around 1802. By 1902 (their centenary), they had assigned just over 11,000 serial numbers, meaning serial numbers around 11,000 were reaching completion in the early 1900s.
Examples from sales records and listings confirm this timeframe:
Serial 11777 → documented as made in 1906
Serial 12963 → year of manufacture 1915
Serial 12100 falls between these, placing it in the late 1900s to early 1910s. Production was steady but not extremely high-volume (a few hundred guns per year on average in that era).
For an exact date, original buyer, and full specifications, contact William Powell directly (gunroom@williampowell.com or via their website). They maintain the historic ledgers dating back to 1802 and offer research/certification services for a fee (some early records are incomplete, but this era is well-covered). This is the most accurate way, as no comprehensive public serial number chart exists for Powell guns.
I am finding Grok a pretty solid way to sort though a lot of "stuff" on the internet and get me pointed in the right direction.
...you can even give it pictures of guns, and proof marks on barrel flats to learn quite a bit.
It's not the definitive "expert" but it cuts out a lot of time and fiddling around.
