Don't do it, an 1851 or whatever!
The damage you can do to your future is incredible.
Here's why:
(1) A juvenile carrying any firearm is in trouble, law enforcement officers will see you seen as attempting to start a confrontation. If you feel in danger, discuss this matter with your parent(s).
Keep in mind any citizen could claim to have seen you carrying a pistol and ask that a Law Enforcement Officer check you out. Explaining you are waiting to be 18 and only carrying a BP revolver will not serve as an excuse.
(2) For concealment, any BP revolver can be seen as such a poor choice as to show the person with the firearm intends to intimidate, rather than self-protection.
(3) If you want to play "Wild Bill Hickock," go to a shooting range.
(4) Any contact with a law enforcement officer if you don't have a permit while carrying, even if a BP revolver, will result in a humiliating experience, cuffed, the pistol confiscated, trip to the courthouse, being jailed. Trying to explain to the arresting officer that the pistol is an antique 1851 version will be to no avail.
You will need bail to get out, and an attorney to represent you. Despite the unreliability of BP revolvers, the Judge will fail to understand and likely convict you with a felony, just as if the pistol was modern, of carrying a pistol without a permit.
(5)With a felony conviction on your record, you will probably denied to: medical school, law school, dental school, most programs resulting in a state license, plus enlistment in the US Armed Forces.
Think about it.