Gibster I just saw your pictures of the D. Marker rifle. I've looked at pictures of a lot of Marker rifles and never saw one with that type of patch box. As far as it being a smooth bore, it should be rifled, however it's not uncommon for the last few inches to be shot out/worn out to smooth. I don't profess to know enough to say they didn't make any smooth bores, just never saw one. James Marker was my great great grandfather and Daniel Sr. was my great great great grandfather. I have seen rifles with that signature. To see them for your self try to get a copy of "Maryland Longrifles" by Hartzler and Whisker published in 1991. They have very good pictures and you'll also see what I mean about the patch box being totally different. Another Marker family signature is that most of them engraved an eagle on a medallion mostly on the cheek piece. I have a James Marker really plain jane rifle, but even it has the eagle even though no patch box at all. My guess is the barrel was restocked somewhere along the way, but you never know for sure.
Raweavey