I've had a couple of Mini 14's and they have been consistently inaccurate. 3 to 4 inch groups at 100 yards was about as good as I could do with either of them.
I decided to try out a new Mini 30 after they made the change to the heavier barrel because I really like the way they feel as compared to an AR. 4 to 6 inch groups were the norm. After a bunch of add ons that were supposed to cure all the Mini 30's problems, the groups were down to about 3 inches at 100 yards. I bedded the fore end to the gas block. That seemed to make a bigger improvement in the accuracy than anything else I did. Groups hover between 1.5 and 2 inches now. To me that is fine for a Mini 30 with the ammo I shoot and what I use it for.
I like the handiness and way the Ruger Mini's feel, but have never owned an AR that shot as bad as a Mini 14/30 does. If they are performing to the design standards that Ruger set, then Ruger should have never made it possible to mount a scope on them.
