I had a thought about JWR’s suggestions on re-balancing your gun collection. While I own a few pre-1899 guns, they are now pricey, even for well-worn guns in shooting condition. I believe an acceptable alternative would be to purchase new reproduction black powder revolvers (the Model 1858 Remington is probably one of the best) and obtain a .45 Colt conversion cylinder. The BATFE does not consider these to be firearms, so they can be purchased with no paperwork locally or through mail order. With the conversion cylinder installed they can fire modern cartridges, albeit at low pressures that replicate historical loadings.
Prices for replica Model 1858 Remington revolvers range from around $150 (used at gun shows) to $275 (new, via mail order.) The conversion cylinders generally run between $200 and $350 depending on manufacturer and features. Most of these are five-shot conversions. While the guns are single action, if handgun ownership becomes restricted for some reason, they are far better than using a rock or a stick for self defense. By shopping around, you can buy these at one at half to a third of the cost of a comparable pre-1899 revolver. At a higher price point, you can also acquire a Ruger Old Army black powder revolver which is available in stainless steel and can also use conversion cylinders.
I have a Remington 1858 Target Model with modern adjustable sights and an eight inch barrel. While it is not very concealable, it is remarkably accurate with .45 Colt ammunition.
Thanks, – The Bruce
JWR Replies: I agree that many types of pre-1899 revolvers are no longer affordable. In particular, the prices of both Colt and Merwin & Hulbert revolvers are quite high, due to strong collector demand. However, S&W, Forehand & Wadsworth, Hopkins & Allen, and Iver Johnson brand revolvers are generally still quite affordable. Many of these are double action top-break designs, making them very fast to reload. (Certainly much faster than reloading a Colt Single action, or any of the blackpowder cartridge conversions.)
It may take some research and patient shopping, but it is possible to find pre-1899 production double action .44-40 S&W or .44 S&W Russian revolvers for less than $700. And pre-1899 .38 S&W revolvers can often be found for as little at $250 at gun shows. See my FAQ on Pre-1899 guns  for more details, including serial number thresholds on various models, to ensure that you are buying a gun with a frame that was actually made in or before 1898.
The main problem with cartridge conversions of blackpowder replicas is that they are slow to reload, since the cylinder must be completely removed from the the gun, and then also a separate firing pin conversion backplate. Another potential problem with cartridge conversions of blackpowder replicas is that State and local laws vary widely. In many states, the use of a conversion cylinder changes the legal category of the gun. And in states with mandatory pistol registration, making such a conversion without prior registration could constitute a felony.
It also bears mention that while the price of pre-1899 Winchester rifles and Trapdoor Springfield rifles have been driven to dizzying heights, many other pre-1899 cartridge rifles remain quite affordable. The 1898 and earlier production Mauser and Mosin Nagant rifles can still be found at bargain prices, especially if you are willing to buy one that has already been sporterized. (“Sporterizing” ruins their collector’s value, but does not degrade their practical effectiveness.)