You're right, Rod. 3, 20 bore balls makes for a great close range, perhaps to 80 yards, IF the balls don't spread enough to miss the vitals. IF there is always one ball through the lungs, then it would be OK to whatever range is the pattern limit. The 40 yard pattern certainly shows good promise.
; I've never used them, but did some tests with 5 or so .457" pistol balls. They didn't pattern well enough for anything but alley cleaning. The triple or double larger ball does have merrit.