Then how do you propose/believe that canister worked?
The period artillerymen did experiment with the rounds as shown. The results of the tests and the effect on target demonstrate how the round works. It is not merely guess work.
The bottom line is that whatever happened in the gun tube, the balls were forced out of the canister by the time they left the muzzle. You have been given the references of both primary and reliable secondary authors. Those that weren't artillerymen are modern authorities. At least one of the modern authorities was also an artilleryman.
If you cannot accept that, then I submit the conversation is at an end or impasse.