I had a .44 cal smoothbore once, made from Shelby seamless tubing, 7/8" octagonal. It had a terrific finish in the bore, and shot very well inded. I carefully ground a recessed choke in it for about 3" in length, 1" back from the muzzle, about .004" to .005" deep. This gave almost 60% patterns which is a very strong Imp cylinder to modified, yet still shot well with patched ball. I used it for snowshoe rabbits with round ball out to about 45/50yd. and it was similar to shooting them with a rifle, except pst 40 yards I no longer made head shots.
: I never used shot except for clay birds ar rendezvous. With 7/8 ounce of #8's and 50gr. 2F, I broke 10 straight at spring rendezvous from the 16 yard line. None of the birds did more than break into 3 or 4 pieces, some only in half, but break they did, and win the trap shoot, I did. I cheated somewhat and used .410 plastic wads with .45 oxyoke fibre wad under with .45 card over wad. For balls, I used a .433" cast ball and .012 patch. the bore size was around .445".