Don't think that all states allow convicts to own black powder handguns or black powder guns of any kind at all. This is cut and paste from the North Dakota State Century code:
"Firearm" or "weapon" means any device which will expel, or is readily capable of
expelling, a projectile by the action of an explosive and includes any such device,
loaded or unloaded, commonly referred to as a pistol, revolver, rifle, gun, machine gun,
shotgun, bazooka, or cannon. For a felon who is not sentenced under section 12.1-32-09.1, the term does not include a
firearm or weapon that is a rifle that has a barrel sixteen inches
[40.64 centimeters] or longer or a shotgun that has a barrel eighteen inches
[45.72 centimeters] or longer and which is one of the following:
a. A firearm, including any firearm with a matchlock, flintlock, percussion cap,
or similar type of ignition system, manufactured before 1899.
b. A replica of any firearm described in subdivision a, if the replica is not
designed or redesigned for using rimfire or conventional centerfire fixed
ammunition or uses rimfire or conventional centerfire fixed ammunition that
is no longer manufactured in the United States and which is not readily
available in the ordinary channels of commercial trade.
c. A muzzleloading rifle or muzzleloading shotgun that is designed to use
black powder, or a black powder substitute, and cannot use fixed
ammunition.
Nope, still not legal for a convict to own a BP handgun in this state and 12.1-32-09.1 deals with violent offenders. Convicts that have an arrest for violent crimes are completely SOL in this state, black powder or not.