I agree ML bores have a wider tolerance than CF bores. And I agree that too tight can affect accuracy. Too loose though that I'm not quite sure of. Now dropping down the bore loose yeah but not when some effort is required.
I usually get the best accuracy when using sabots when I can start the sabot with my thumb and then get a smooth pressure on the ramrod all the way down to the charge. IMO that give me enough pressure to engage the rifling and is tight enough for the skirt to open up providing an efficient gas seal.
Not saying Ron does it because he's been shooting a long time, but I think a good deal of shooters have accuracy issues by using too tight a sabot and improper loading technique which may damage the sabot, bullet tip or both.