Seems to be unclear as to what manufacturer(s?) built the side-button guns although Hiller claims this latch was patented in 1901 without saying by whom.Don R.
Thanks for that, Danny. When I acquired my example in 1993, I recorded it as FLZ based on Hiller's discussion - good to know others have agreed. A small note though: at the time these were made, the town was likely still known as Zella St. Blazii.Don R.