Re: Help wanted
There are advantages in the turn-off design. The breech is bored with a cavity that serves as its powder measure, the ball is placed over it and the barrel is screwed on. The bore of the barrel is a little smaller than the ball which assures a good fit of ball to accurately bored barrel minimizing loss of pressure. Need for patch and wadding is eliminated.
In longer barrels the turn-off was more accurate than the patch and ball smooth bore. Memory recalls a late 1600s English story about Prince Rupert hitting the weather cock on top of a steeple twice with his pair of turn-offs.