I honestly don't think it matters. I have seen very accurate guns in any type of action and really innacurate guns in every action. I think it boils down to a bolt action is probably cheaper to produce so you end up with a better made gun for the money. And most bolt actions have better triggers which helps a little.

For the average shooter with a quality weapon I don't think it matters, any action has the capability of being accurate.

I think a lot of AR shooters would argue the semi auto target rifle part.

Technically a single action break open should be the most accurate.

Paul