Improving the stock mini.
1.You need to glass the action into the stock. The factory fit is way too loose, and lacks the needed barrel/receiver consistency to the stock to achieve constant barrel/receiver tension/placement.
2. The barrel is way too thin, so the options are to either tension sleeve it, or just replace the less than stellar production barrel with heaver custom unit.
3. Since it is a Ruger, the trigger is going to break way too heavy. A trigger job will crisp and bring the pull weight down to usable 3.5 lb level.
4. The gas system is ported too large for most ammo, and it tends to over work the system. If you going to run stock barrel lengths, you can sleeve it for a smaller fixed port or install an adjustable system to the factory unit to tune it for your loads.
Full blow custom,
1. Double lug the receiver and use tension screws for receiver/ stock lock-up instead of the single point trigger group in the bedded lam stock.
2. Install a 26" broach cut barrel in 22PPC (got to love the mini-30 action), after you have squared the action and faced/lapped in the bolt.
3. The trigger pack is mod’d out to a M-25 style FCG for a break weight just above 1.5 lbs.
4. Now that you are running a longer barrel, the stock gas system is too far back in the barrel from the muzzle and the gas system/port needs to be pushed forward. Since you will need to make a new stock for the lugs/scope alignment anyway, you drop the carbine style gas system and install a M-14 piston gas type system father down the barrel. The New Mini rifle is now a short action M-25 with a barrel long enough to do the PPC round justice. And since you can shut off the gas system, if needed, you can run the rig as a bolt action using fire form cases sled’d into the action one shot at a time (read in the .3’s). When it comes to a scope mount system, the Ruger is a rock solid system second to none, and a much better mount than anything currently offered for the M-14 rifles (barring tapping the receiver). Granted that the new rifle looks very little like the shorter Mini, the receiver is still a Ruger mini, so the end product is a custom Mini.
As RAF pointed out, the full blown is not something that you may want to do on a new rifle since the prices are much higher now, but back when you could get a used rifle for under $200, it justified the total build price/machining time since you would end up using the receiver, the bolt, and the FCG parts. The stock, the barrel, and the old gas system with opt rod where sold off, so in the end, you dam near got the used rifle/needed build parts for free.