I have heard from folks owning "new" Mini-14s (with the "heavier" profile barrel) who usually get 3MOA using the best (for their particular Mini-14) factory ammo. Sometimes a bit better. Handloads may shrink the groups further.
Mini-30s always had a "heavier" profile barrel, but it appears that the newer ones have a slightly "heavier" profile than the older ones. Therefore, there was not as much change in accuracy as there was when the Mini-14 went to the "heavier" profile barrel. Again, finding the "optimal" ammo for your particular Mini-30 (or Mini-14) can make a considerable difference in group size. Most experienced Mini-30 users report about 3 MOA with "factory" ammo which their Mini-30s "like". Some do better than that, and, again, handloads still better usually.
Assuming a Mini that is mechanically sound, properly lubed, and properly broken-in (200-300 rds), reliability should be excellent with Ruger brand magazines.
Many reliability issues and most accuracy issues with modern Minis can be traced either to poor quality ammunition, and/or poorly made magazines.
A 6 MOA group with a modern Mini indicates that something is amiss. It might be easy to fix, such as shimming the inside of the stock, or require a trip back to Ruger. For this reason, I strongly advise folks to leave their Ruger firearms bone stock until they are certain that the firearms function properly. Ruger hates user-done modifications; always has.
Keep in mind that all Minis are lightweight, handy carbines. They were never intended to be "precision" firearms. It may be that a "particular" Mini, right out of the box, will not meet your MOA expectations, but with a little, inexpensive "DIY" work may come pretty close to 2MOA. Maybe not.
FWIW, my highly modified 186 series Mini-14 (Pencil Barrel) will shoot about 2-1/2 MOA using high quality generic milsurp handloads. IOW, the handloads are not "tailored" to suit the Mini-14.