Most of my best appreciating firearm assets are because I aquired them cheap rather than age. The biggest is probably my Mauser 660 .243. It’s the model 66 in Europe. I remember my dad buying it for about $300 in the early 80s. Today you don’t see them sell often. When you do they can easily fetch $2500 and sometimes much more depending on barrels and options. My son shot his first deer and first bear with it. It’s almost too pretty to take into the woods. There’s no amount of money that would buy it.