I found this shotshell while metal detecting. I think it says Kynoch & Co “No 12”. The bottom also says Kynoch. I’ve looked for similar headstamps with the wording in the recessed ring and didn’t see any. All of the others I saw are flat with stamping.
I tried to flatten it out and measure it I think the overall length would’ve been about 3in. It’s been pretty mangled over the years by the plows.