Lot of guys shoot the power belt i even shot the round ball last year with success got a 5x4, just make sure the gun shoots it well, mine wouldn't keep a group with them was using 100 grms pyrodex with 345 grain power belt , just for elk use as heavy bullet you can shoot well.

PaRu,
I have been looking at the Thompson conical and the Power Belts.
I will be testing both in my muzzleloader. I have been using sabots
and took dandy 7 x 6 bull in New Mexico at 178 yards in 05. I have hunted
elk for the last 15 years and been successful with a centerfire but the
new inline muzzleloaders definitely provide a more challenging hunt.

Thanks again for the info

My muzzleloader has a 1:32 twist, so it shoots best with relatively long bullets. As such, I use the Thompson Maxi-Ball, which is a fairly long conical. The PowerBelt bullets are also fairly long and are legal in Colorado.

I'm not sure what the twist is in your rifle, but if you were considering sabots then I'd guess it is fairly fast and so you want a fairly long bullet.

Bottom line is you need to try a variety of bullets and loads to find what works best for you in your rifle. Good luck!

CVA Powerbelts. Hornady has a line of Great Plains bullets too.