Welcome, NB. Forum member Steve Zihn makes guns just as you were querying about.
While I have and enjoy a 14 bore rifle, I would have preferred it to be a 16, although I do shoot 16 bore balls in this rifle with a
.034" patch, I also shoot 15 bore balls with the same patch as well as .682" with .021" patches. True 14 bore is .693", but my
barrel has a .690" bore, & .714" groove dia.
I do have a friend with an 11 bore rifle (.75")in which he uses .735" balls & a substantial patch.
Our rifles both "stagger" moose.
Another forum member, Dphar (Dan P) built a 1/2 stocked English 16 bore Flinter, but his is right handed.