Only difference between the II and III is a loaded chamber indicator or a lock, neither needed. Some Mark II's were drilled and tapped and came with a base. Accuracy is superb even the Mark I was fantastic.
The .22 has it's problems with ammo so the right stuff needs found. I like CCI, Mini Mag HP's for general use and Fed bulk is decent but if you find the right ammo, this is what can be done at 25 yards. 9 in one hole and my screw up with the last shot.