The substitution of the word choke rather than "not for ball" in the case of the recessed choke is rather obvious. The solid ball did not expand when passing through the recess thus presented no problem in going through the "Choke".
The whole bottom line was any solid ball fired needed to be of a small enough size to pass through the choke. At this point in time, the solid round ball was the most common projectile used in a shotgun for larger game. A solid ball larger than the choke diameter becomes an obstruction & can cause a bulge, or what the British called "Lift the Choke".
