There have been many, many threads on this and other forums across the street, about the Mini 14 and it's accuracy (or lack, thereof).
Some time ago, there was a company (in Texas, I believe) that did work on the Mini 14 and claimed to have excellent results.
The work involved everything from the 'clamp' that secures the stock and barrel (end of stock) to replacing the barrel with one similar to the AR in weight and configuration.
Some owners have used the barrel weight that slides on and can be slid forward or back, to regulate (somewhat) the vibrations set up in the barrel when firing.
How much success these persons have had. . . . . ??????????
This barrel weight looks like a big doughnut. I've seen it in the CTD catalog.
You might have success with this. I don't think that they are very expensive.
Bottom line. . . . the Mini 14 has never been known as a 'tack-driver'.
IHTH.