I am actually surprised how accurate it is.
With practice, you can drive tacks with them. Their downside is they are more difficult to tear down and cleean then some other brands of inlines. But as far as accuracy, it will stand tall with my Encore,CVA and both Knights out to 125yds.
Are you using a #11 percussion cap?
If you are, you may not want to use the powder pellets. Three of the same mod. rifle had trouble shooting the pellets with the stock nipple.
One more thing I've found with the Powerbelt boolits, much more than 100grns. of powder, you will probably see your accuracy start to fade. That's been my experience with them anyways.