Sounds like min' s aint what they used to be.
My first Mini-14 a 181 series would do 1" -2" with the iron sights that came with it.
Other Mini' s I' ve owned later shot larger groups, one terribly larger about 5" .
The one I own now, another 181 series, shoots just as well as my first.
I' ve heard talk that Ruger contracts out the production of the barrels for the Mini but have no reliable info on this. Could be the reason for varying accuracy though.