In old documents “J” is sometime rendered as “I” (or vice versa?). It may be worth searching for JSH as well as ISH.
Thankyou for suggesting this. It had occurred to me, but as it is typically used by the Classically-educated, there being no "J" in Latin (Iulius Caesar!), to indicate their erudition, and that wasn't a description I linked to a barrel-maker, I'd set it to one side. However, the turn of the 19th century was arguably sufficiently infused with Classical motifs for tradesmen to affect them, and in any case I'm having no luck with "ISH", so it's a good moment to revisit that one.
Edit: just re-read this and it struck me as thoroughly pompous - I do apologise! This was not my intent.
Edit: I also have to stand well-and-truly corrected in the light of the following : "REVOLUTIONARY WAR PERIOD ENGLISH SILVER MOUNTED FLINTLOCK OFFICER’S PISTOL, BY “GRIFFIN” ca. 1760 [...] iron barrel with two (2) London Gunmaker Co. proofmarks and an “I.G.” (Joseph Griffin: Please see “Gunmakers of London…”, pg. 212-213) maker’s mark." (
https://www.ambroseantiques.com/fpistols.htm)
