Black powder muzzle loaders are not firearms at the federal level. Black powder cartridge arms usualy are.
They are still firearms at the state level in many states. Some states have seperate less restrictive laws for them, and some states treat them no differently under the law than any other firearm.
Meaning a black powder long arm is a long arm, and a black powder handgun is a handgun.
You would need to look up Florida law, not the federal law for your answer.
Usualy that requires looking up both the law and case law related to that law for the clear definition.
If the law makes no distinction between them, then you must assume laws written regarding "handguns" refer to handguns in your state.
Also look at the definition of firearm in your state.
Some state consider them anything that expels a projectile with the force of an explosion/combustion. That would include black powder arms.
Some brief searching and I found this:
6) "Firearm" means any weapon (including a starter gun) which will, is designed to, or may readily be converted to expel a projectile by the action of an explosive; the frame or receiver of any such weapon; any firearm muffler or firearm silencer; any destructive device; or any machine gun. The term "firearm" does not include an antique firearm unless the antique firearm is used in the commission of a crime.
(1) "Antique firearm" means any firearm manufactured in or before 1918 (including any matchlock, flintlock, percussion cap, or similar early type of ignition system) or replica thereof, whether actually manufactured before or after the year 1918, and also any firearm using fixed ammunition manufactured in or before 1918, for which ammunition is no longer manufactured in the United States and is not readily available in the ordinary channels of commercial trade.
So the definition is slightly different than the federal one, but not too much. It needs to be a replica of a design made prior to 1918 that does not use fixed ammunition.
No modern black powder designs.
I however do not know all the potential statutes that apply outside of that particular one. You need to do more research on your state law, and possession at various ages.
Every state is unique concerning black powder guns.
but I purchased one mail order from DGW when I was 16.
Just because you can purchase something does not mean it is legal. You can do that in most states because they are not federaly required to go through an FFL even when crossing state lines, but in many states you would have still commited a crime.
There is a large number of things I could purchase from around the nation without violating any federal laws and have shipped to me that are a felony at the state level just to possess in my state.
