Until about 1988-89, Ruger sold Mini-14 20 rnd mags to the general public, but sold their 30's only to LEO's.
Bill Ruger actually helped write parts of the AWB, and did so in such a way as to "protect" the Mini-14 and other Ruger products. He actually said in a TV interview that he never meant for Ruger hi caps to be sold to "ordinary citizens", and that no mere civilian needed more than 10 rounds.
Well, screw ole Bill.
I would not look for hi caps from Ruger, unless they have put in company leadership that wants to make money rather than run scared.
Fortunately, Federal Ordnance aka Precision Magazine Inc aka PMI made mags as good as the Ruger factory hicaps.
BTW, PMI 20's, 30's, and 40's all run equally well, which is 100%. 20's are tiny little guys. 30's fit in the same pouches as USGI 30's. 40's are REALLY good from a capacity standpoint (two strapped together gives you 80 rnds on the gun), and I keep one plugged in my nocturnal social purposes Mini. But they hang down quite far. Forget firing prone with a 40.
Investment? No, I don't think so. Consider it more a "beater".