Eightbore and other have it. The money is made on "the flip", not in the long term buy-and-hold, except in exceptional cases.
Discounting the "enjoyment factor", the real ROI on most gun investment pales in comparison to long term returns in the market. What is often forgotten is the real cost to securely store (think safe w/ humidity control), properly insure, and maintain the guns. This eats into long term returns but is rarely considered in t people's mental arithmetic. And if you need to sell your guns quickly, you'll find that diversified stock and bond portfolios are much more liquid than fine guns. That is the cold reality of it.
I love to see the value of my quiver of guns increase like the next guy and I wouldn't trade it the money I have spent pursuing the guns for some more shares in Cisco, but go into the inestment process with a clear understanding of what you are trying to do. If it is PURELY to make money, I'd look to other avenues.
Ken
