Unknown to most persons, except lawyers and those ATF victims incarcerated in federal prisons, it is a federal crime for the following nine categories of persons to possess firearms: persons who have been convicted of a crime potentially punishable by more than a year (a bad check conviction 40 years ago can suffice), fugitives, users of drugs or marijuana, mental defectives, illegal aliens, dishonorable dischargees, renouncers of citizenship, those subject to domestic restraining orders, and those convicted of misdemeanor domestic crimes of violence (threatening your wife 20 years ago can be enough). Title 18, U.S. Code, Sections 922(g) and 924(e) mandate a penalty of up to 10 years, and in the case of persons previously convicted three or more times of drug crimes and certain others, a mandatory 15 years to life with no parole. (Someone 50 years old convicted at age 19 of, say, three pot sales, thereafter becoming a model citizen and caught with a gun hunting ducks 30 year later is an Armed Career Criminal subject to the enhanced 15 years to life.) Any person purchasing a modern handgun, rifle or shotgun from a retailer must sign an ATF Form 4473 swearing that he is not in one of these categories. Lying constitutes yet another federal crime. There are several tens of millions of Americans that fit one of the above prohibited categories. There are also over 10,000 such persons in federal prison for illegal gun possession, including over 2,000 with the enhanced 15-life penalty. Horror stories abound and I can think of two published decisions off the top of my head in which people were sentenced to 15+ years: a duck hunter caught in hip waders with duck decoys and a shotgun and a man caught with a Model 1908 Colt .25 caliber automatic pistol with no ammo, no clip, no grips, and a slide rusted closed.
Federal law exempts antique firearms from all gun controls. Title 18, U.S. Code, Section 921(a)(16) defines antique firearms as all guns made prior to 1899 as well as all muzzleloaders made anytime, and replicas of pre-1899 cartridge firing guns made anytime, provided that such replica uses cartridges "not readily available in the ordinary channels of commercial trade." (Note: Cartridge firing machine guns and short-barreled shotguns are still illegal regardless of when made, under Section 5861 of the IRS Code, Title 26, U.S. Code.)
Muzzleloaders (so-called black powder guns loaded from the end where the bullet exits) are legal, whether original or replica, regardless of the date of manufacture. You can buy them by mail order. The most practical to own for self-defense are the so-called cap and ball revolvers originally made between 1840 and 1870 and used by Wyatt Earp and other gunslingers of the West. Numerous companies make and sell replicas of these six-shooters. Many can be had for $100 or slightly less. A good choice would be the .44 caliber Model 1860 Army. To use them you need powder, lead balls, wads, and percussion caps, all readily available in gun shops and sporting goods stores.
Between 1858 and 1898 millions of cartridge firing guns were made by Smith & Wesson, Colt, Iver Johnson, Remington and numerous others in such calibers as .22, .32, .38, .44, .45 and many dozens of others. Believe it or not, these original guns (totally exempt from federal gun controls) are so abundant that they can be had for $150 or less at any of the dozens of gun shows held in this country from coast to coast on any given weekend. At nearly any gun show you can pick up a very workable .32 or .38 S & W revolver, a 12-gauge double barrel shotgun, a 7mm German Mauser bolt action military rifle, and many others for less than $150, all made prior to 1899 and legal for anyone to possess.
This third antique category will not be dealt with in this article simply because this author does not know of any modern made replicas of pre-1899 cartridge firing guns that use ammunition cartridges not readily available in the ordinary channels of commercial trade. ATF claims that they have no list of guns in this category and any request for antiquity classifications of such will be dealt with on a case by case basis.