RE: Is the Savage M10 smokeless muzzleloader legal in Michigan
Some people debate that "commercially manufactured black powder substitute" includes smokeless powder as it is being used in place of black powder in the rifle. I think this is a very simplistic argument that will not get you very far if you actually went to court with it. The intent of the statute is that a substitute is something equivalent performance-wise, which smokeless is not. This vaguary is why many states have changed their language to exclude "nitrocellulose-based propellants".
If you call the MI DNR they WILL tell you that the Savage is not legal to hunt with when shooting smokeless, though you could use any BP sub in it legally.