I've got a Springfield Armory Range Officer in 9mm. Bought it because I always wanted a 9mm 1911 and all my pistols are the same caliber. The first thing I did was to buy a bunch of 10 round Cobra mags for it. They work flawlessly compared to the factory mags. Since I have had it, it has been worked by Dave Salyer to make it into an informal bullseye pistol.
Salyer highly recommends shooting 115gr XTP (or HAP) bullets at about 1150fps for best accuracy with the factory barrel. There are several companies including Hornady that have a load that fits this discription if you don't reload. However, I have found that Fed American Eagle 147gr FP shoots almost as well with less recoil and lower cost.
I also had a poor experience with Wilson, but it was with their custom ammo. They had a sale going on for their 9mm match ammo in 400 round bulk boxes. They claimed it was manufactured to high standards and blah blah blah... So, I ordered a box of 400 for testing. The first time out to the range, the ammo locked my gun up. I was able to clear the pistol at the range and figured it had to be a fluke. The very next mag, it locked up again. Long story short, after checking the ammo that night, I found over 50 rounds to be out of spec and loaded to long. I contacted Wilson to address the problem. I only received a short email that thanked me for bringing it to their attention. No offer for a refund or replacement. Follow up emailed never got a response. I won't be dealing with Wilson any more.
The Springfield really likes Creedmoor Sports 9mm match ammo. If you are looking for the most accurate ammo for your 9mm, I would highly recommend it.