I have watched through my binocs, balls being shot from a smoothbore by one of the lads here (Hatchet Jack) on a 92 yard target. I have seen a number of them heading straight at the target, yet seemingly only feet in front of the target - they veer off to one side or the other- quite randomly, to miss the fox target by 2 feet to 3 feet. Hatchet Jack's load was a mere 65gr. 2F, thus he would be lucky to beat the speed of sound.
The visual shows the balls appear to take on a spin and the dramatic veering appears like a curve ball in baseball.
Now - the more powder used, thus generating higher speeds, showed slighlty better accuracy at the longer ranges, perhaps due to the ball getting out there further before taking on that accuracy destroying spin?--
That is a supposition on my part.
Another of the 'lads' here complained about his 20 bore shooting left. Taylor and I tried it, finding it shot quite centred for us. The difference must simply be the way we see or saw the barrel and blade, compared to the owner.
With this fairly long barreled smoothbore 20, I shot a 5-shot, 3" group at 50yards from the bench. It was a nice round group, but I only shot the one group- no more for proof of capability.
I cannot even come close to that with my own 20 bore (never), thus I have relegated my 20, to only shooting multiple little round balls at clay targets. My best at a normal 8"x11" target was 4 hits for 5 shots.
4 hits out of 5 shots on the 8"x11" page was actually better accuracy than the first place shooting in the first and last 50 yard smoothbore chunk match we held at Hefley Creek Rendezvous. The best target of all those shooters, had 5 hits (prone over a chunk) for 10 shots fired- 3 on one target and 2 on the other - supposed to be 5x5.
I think Dan's got a good handle on normal SB accuracy, or inaccuracy as it should more accurately be called.