All of them produce an accurate bullet. It boils down to design or makeup of the bullet and the price of them.
Hornady is the most cost effective with their XTP's. Speer Gold dots are normally a real good shooter. Sierra I do not use all that much. I do not like their cost.
all of these bullets are good ones but in my ML I have always gotten better ACCUR. out of the SPEER GOLD DOT 250gr and 300gr with the best being the 300gr. GD
In this case I am asking about centerfire bullets that will be used in a muzzleloading application with sabots, .325 caliber or less. I was not very clear about that.