I tried a 3 ball load 000 in my 6.5" 41 mag Blackhawk, using a Rem 410 wad with the superfluous petals trimmed. 16 gr H110 which is quite hot. Two balls hit close each time, the third missed the target. This was soft (pure) lead with some buffer. I think with hardened buckshot, it might group all three quite tightly.
Anyone else tried this in a rifled barrel? How about a 444 ... that should take 4 35 cal (000) balls in a plastic wad or 3 larger balls naked. In theory, the spin should make the balls stable and they should group very close. But in practice, how much spin is imparted, and how much flattening takes place? Interesting question for those who could use a buckshot load now and again in their 41, 44, or 444