Where Federal law and Colorado law both prohibit convicted felons from possessing firearms, we know federal law does not recognize some older-style muzzle-loading guns as firearms.
I recall Judge Murphy referred to BM's supervised probation officer to cite BM allowed the use of a muzzleloader during his convicted felon status that is not set to be lifted until late June 2023, (providing no violations with terms of his plea agreement and/or probation).
However, take note that not every state has been willing to accept the use of muzzleloaders by convicted felons.
For example, I just learned that Nebraska rejects the notion that muzzleloaders are NOT firearms:
Nebraska law, as set in State v. Tharp, 22 Neb. App. 454, 854 N.W.2d 651 (2014) noted that Nebraska law 28–1201(1) states that a firearm is “any weapon which is designed to or may readily be converted to expel any projectile by the action of an explosive or frame or receiver of any such weapon.”
The court held that the black powder or muzzle loading guns, in that case, were “designed or had the ability to expel a projectile by the action of the explosive black gunpowder.”
In other words, please be aware of your subject state laws before acting on the muzzle-loading gun advice for convicted felons.
But more importantly, I don't know if the Sheriff's List cited by BM's motion includes any "muzzleloader" non-firearm. Perhaps one of our firearm aficionados can review the seizure list and enlighten us.