Thank you so much, Alexender,
For sharing this unique Late-Gothic source of illustration!
As you mentioned, it is datable to ca. 1480, so the use of balls is shown, documenting a remarkable step forward compared to 14th c. clod shot.
On the other hand, of course, the loading procedure
was all the more difficult as it required employing a very special thin iron stick
to sort of center-string all the balls thru their holes in vertical succession!
Eight superimposed loads are depicted by Martini, which doubtlessly meant 'rapid automatic fire' as these shots must have been discharged within a short span of time of ca. 4-6 seconds once the foremost/upper had been ignited ... imagine such a dramatic psychologic impact when everyone else only had one single shot in their guns! Aiming the muzzle in the direction of the opponing army must have sufficed to wield a horrible amount of excessive firing power.
For clarity, please allow me to repost that 'photoshopped' image from your clever input!