The key to acquiring guns as an investment is to buy them right. If you buy a model 58 right now for $900 you may or may not make any money. If you buy it at $400, you have nowhere to go but up. I never buy a gun at market price. If I can't buy it cheap, I don't buy. This requires patience, persistence, and research, but it pays in the long run. I quit buying guns to fill an immediate need years ago. My accumulation is more of a hobby now. Best deals I've made are usually online. I let 5-600 go before I pull the trigger on one. I hit pawnshops once or twice a month, and find something of interest maybe once every three or four years.

Better yet, don't consider firearms as an investment, consider them as an inflation hedge that you can play with.