The problem with using guns or treating guns as an investment is that they are a horrible one. If you through $1000 in a metal box and buried it in the sand for 5 years you would still have $1000.
If you spent $1000 on a firearm ($1000 isn't very much, just proving a point) and put it someplace safe, rust free and never touched it for that same 5 years it maybe worth $1000, it might be worth $500 or it might be worth $1300. If it sold well, then Winchester or Remington or whoever will have flooded the market with them and it will be worthless. If it didn't sell well, but was an interesting caliber hopefully you will get your money back.
I beleive the market shifts a lot, there was a time when you buy a 2nd hand post 64 M94 in 30-30 $200-250 any day of the week. And the gunshops were selling new ones for $350. Of course FN shut down the New Haven plant and now any m94 is worth more.
The worst case scenario is the M95 Winchester. My whole life I lusted after a M95 in 405 Winchester just like Teddy Roosevelt had, hell I had never even seen one in that caliber. Owned a couple in 30-06 and 30-40 Krag that were built by Browning in Japan, and even owned a 7.62x54R as a war bring-back. The ones that were for sale were $6000, and now they are worth half that as Winchester dumped tons of new 405's into the fray.
Handmade rare guns by big makers are a good investment. $10,000 would have bought any turn of the century English built double rifle
trade gun in 2000. Something like a Army Navy 450/400. Those same guns today are pushing $20,000, and if they are really clean a premium over that. In the 80's that was considered to be an OddBall caliber and you could have gotten the same rifle for $4000. So in this case of English double rifles yes, it's not a bad investment $20,000 in todays market for a $4000 investment in 1985.
If you had $100,000 and bought a Fuchs bolt action double rifle, shipped it to America and never handled it but put it for sale in one of the bigger double rifle sales shops like Hallowell, Beretta of Dallas, Westley Richards or Griffin and Howe it wouldn't move for $50,000 even though it's 3 days old and cost $100,000 to make in Germany. Why? Because they are considered to be an abomination by the gun world. I personally think they are neat, but since it isn't fish nor fowl in the realm that it is a 6 shot double rifle bolt action fed slut, most purist gun snobs don't like them.
Guns are a horrible investment 95% of the time.
I am not saying use and abuse it, but don't be afraid to use it.