A frequent reader sent me an e-mail about collecting guns. I answered his e-mail and realized it was turning into a post. So after a little rewriting….
The best advice I can give a potential collector is to collect what you like. If you like military bolt action rifles, then that's an excellent place to start. On the other hand, you might like handguns, shotguns, etc. I like "mouseguns," handguns, and military firearms. Don’t forget though that a collector must specialize; even “mouseguns” is a huge field.
I tend to shoot what I collect (with a couple of exceptions) so anything I buy must be mechanically sound and not “demilled” (made inactive). I don’t want a Thompson sub machine gun with a dummy receiver no matter how many original parts they hang on it.
I select guns based on condition and originality. That is, I don't collect sporterized military rifles, but someone else might find it a fascinating field. I make sure that any gun I buy has all the parts the factory intended and no extras. Similarly, serially numbered parts must match.
In fact, the more you know about a particular gun, the easier it will be to spot problems that reduce its value or historical interest. A good set of reference books is a must. By the way, I loathe electro-penned imports marks. I own a few with these marks, but I’m not pleased.
I hope to find cartouches (inspection stamps in the wood that the Federal inspectors used before and during World War II and slightly beyond), but an arsenal rebuild might not have them. I'd rather not buy rebuilt firearms, but complete originals are not always in my price range.
Condition is important. I've picked up a few diamonds in the rough before and "rescued" them, but it takes a lot of work and it's better to buy guns in good condition in the first place. I look for a gun with a nice, bright bore with strong rifling. I want the gun to be free of rust and pitting from previous rust removal. The stocks/grips should look decent although a little wear is not a problem. The action should work and feel like it is working. That is, the bolt shouldn’t feel like you’re pulling it out of concrete, the trigger should activate the sear, etc.
As far as preservation, a lot of military guns will come coated in cosmoline and it takes a lot of work to get it all off. Once you have the cosmoline off, there’s still dirt and grime to worry about. Be careful of using solvents like turpentine or alcohol. You could wreak a sporting arm's finish quickly and not really help a military gun’s finish (usually linseed oil rubbed into the wood). Because I want to keep the gun as original as possible, I don’t refinish my guns (I made an exception for my M1 Garand that didn’t have an original finish).
Inspect for active rust. If you find any, you'll need to remove it with dental picks or similar tools, but go slow and don’t scratch the non-affected area. Once cleaned, I usually apply a thin film of CLP BreakFree to the metal and I've been known to rub a silicone cloth over the wood and metal as a rust preventive.
Guns should be stored in a reasonably dry environment. If you use a gun safe, the sealed interior becomes a micro-environment and it can get humid in there. You'll probably need a dehumidifier or drying agent in the safe.
There may be a time when you want to sell a gun from your collection. Be careful because it's easier to break the law when you sell than when you buy. For instance, you can’t sell a handgun to someone who doesn’t live in your state (there are exceptions for Curios and Relics if you and/or the buyer are licensed depending on the circumstances).
Guns tend to hold their value over time and if you keep them long enough, you can make a profit. But, you can't sell them in such a way that means you're "in the business" of selling guns (i.e., selling a lot at once). Selling them on consignment through a gun store is a good idea although it'll reduce the amount you'll make from the sell. Still, it beats having the ATF knock down your door at 4:00 am. I don’t like giving that advice, but it’s a reality in today’s world.