Some questions for a discussion.

When posting the photos, I was thinking the bore gun was rifled and a double rifle bore gun.

But it appears to be smooth bore and indeed appears to have no rear sight.

So is this 4-bore meant to be used as a shotgun?

Perhaps for UK sea marsh waterfowling? Sort of a carryable punt gun?

Second question/discussion point. Were the old African elephant hunting bore guns in 4-bore and even up to 8-bore actually smooth bore guns? I know a lot of the 8-bores were rifled, but assume most of the 4-bores were smooth bore? Perhaps there is also an element of the time period in which the bore guns were made, earlier guns being smooth bore? Comments?