Any "special model" Ruger will have a coin or emblem somewhere on it to identify why it's special. My guess is 1) you got really lucky and found a diamond in the rough in a factory stock, 2) it's an aftermarket stock , or 3) someone built a stock of their own. No bets from me on which is the truth of it, but I'll say it's not a "commemorative model" or anything special otherwise it would be marked as such.

How does it shoot? It has a scope on it and it's in the truck, so I know you've put some rounds through it! I'm always interested to hear how well Mini's perform.