Would you classify what the old boys called a fowling piece as a smoothbore shotgun?The smoothbore shotgun was designed only for shot , for a single projectile it has to be a rifle. Any other smoothbore to shoot a ball are military made weapon.
Writing in England in 1789, William Cleator made it seem shooting both ball and shot from a fowling piece was common.
"Some determine the charge of a fowling piece, by the weight of a ball of the exact size of the caliber; estimating the weight of the powder at one third of that of the ball, whether it is proposed to shoot with ball or with shot; "
Spence