I've been having an exchange with a very knowledgeable gun expert in UK that leaves me somewhat mystified, probably because I'm not a professional gun guy. I have always assumed that when A&D patented the box-lock action 11 May 1875 (hammerless box-lock action), that all A-D patent box locks subsequently used a top lever. I was told that this doesn't necessarily have to be....a box lock could just as well have a side lever.

Now I realize how much I don't know. Has anyone ever seen a side-lever box-lock?

Yes. I had a Army Navy 20 bore that had a side lever. I’ve seen others as well.

Here's one example Sidelever

Ken

Merci and Thanks. Ask here - and an answer will be forthcoming.