Dunno - a $100 SKS from 2005 is worth 3 times that.
Anyone can pick out an example of an outlier -- I can probably find a specific stock, or commodity, etc, that performed phenomenally over a specific period.
Hell, I can probably find examples of guns/ammo in the run-up during 2008 that had even greater inflation in value than that.
Unfortunately, all of those examples are just not indicative of the vast majority of firearms, ammunition, and accessory values over time.
I like how much money I've made on AAPL stock in the last two years, too...but that's also not typical of nearly any other stock for sale for any other company.
It's a fun idea -- I get it. I wish it were true. If folks feel like they're going to make a buck or two or buying guns and ammo, then go for it. It may work out for you, who knows.
Unfortunately, the economic reality just doesn't bear itself out as being a serious competitor or improvement to the various other conventional economic investment possibilities.