I've done some fairly extensive testing with my Mark II Competition model. Using a rest and a red dot sight at 20 yards, the best ammo I have found is CCI Pistol Match. Federal Gold Medal is nearly as accurate, but has suffered from failures to fire in my pistol and several others in my club. The failures happened in two lots of ammo. Nearly as good and much cheaper has been T-22. CCI Blazer also good. Most other bulk ammo sold at promotional prices OK for practice, but clearly not up to the best in terms of accuracy. With my pistol, I've found that cleaning after about 1200-1500 rounds helps maintain reliability. I'd suggest getting an economical brand for practice and using premium ammo for matches. Make sure the sight adjustment does not change, or at least learn what adjustment is needed when you switch between the two types. Again in my pistol, impact point at 20 yards does not seem to change much with different brands. However, I fired some generic "white box" ammo from Olin last week from a rest and it shot about 2.5 inches high from a rest, but seemed about on when I shot in a normal one-hand bullseye grip. Will investigate this more.