Is this the same Accuracy Systems that used to be in Texas about 15 years ago? If it is, I had a 20" 1-9" twist barrel installed with an M14 type flash suppressor and a complete black parkerizing job by them. While they had my Mini, they also did an accurizing job on the trigger and installed an adjustable over-travel screw as well - free of charge. When I got the rifle back, it didn't shoot or handle like any other Mini 14 I'd ever used. It was a totally different animal. It was far more accurate (a tack driver), and the balance was far better. The trigger was nothing short of superb. It wasn't cheap to do, but it wasn't outrageous either - no more than what it would cost to do the same to an AR (less, actually). I added an MPI fiberglass stock with a more standard length of pull, and the rifle was quite unique. The appearance was like a hybrid version of a true "Mini M14".
Despite all the dramatic improvements, I still ended up selling it to a friend. After all, it was still a Mini 14 at heart with all of it's investment cast components. It wasn't, nor would it ever be, Mil. Spec. It never failed me though, and it's still preforming as well for my friend.