It is just simply a fact that a bolt action is inherently more accurate. I am not sure how anyone could think otherwise. It really is common knowledge in the shooting world.
I haven't read this thread too far along yet, but just wanted to comment. While this may be accurate, I don't think the "shooting world" is thinking "muzzleloaders." They are really thinking about centerfire arms. The type of action, whether break open, bolt, falling block, etc. impacts a whole ton more variables in a centerfire rifle than it does in a muzzleloader. So, to apply that logic to muzzleloaders is not exactly apples to apples. There is no way you will ever convince me that a "bolt action" muzzleloader has
any advantage over an Omega-style, falling block type action. It's all in the quality of the parts and the touch of the person who puts it all together.