Thom2
It is not that simple. There is a wide tolerance on bore diameters in muzzleloaders,they run from .497 or even .496 in rare cases and up to .505 just using .500 caliber as an example. The .496 to .498 is what the crush rib is designed for and works good with. The next one up in size is the MMP HPH24 and the black Harvesters which are the same thickness of petals, after that the next thicker one is the MPP 12 then the short black MMP. What you need is the one that makes every thing fit right to your barrel. Lee