I've never owned a CZ 550, but I do own a ZKK 602, plus assorted 21 H's and 21 F's. I also own about 40 pre-64 Model 70's, and for my money the Model 70 is the slickest factory bolt action ever made. I have taken over 90 head of African plains game with my Model 70 in .300 H&H and never had it fail me. If you feel the need for a stock bolt, by all means add one, but I never found that to be the case with a .300 H&H. The .375 and .458 are another matter, and I certainly have a pair of them in my .450 Watts Magnum Model 70 (which has also been to Africa and performed flawlessly).

I have a pair of Model 70 target rifles which collectively have about 6000 rounds of ammunition through them with superb accuracy out to 600 yards, and never a bobble in rapid fire which wasn't attributable to the operator.

The only superior feature of the CZ is the integral bases for a scope mount, but the safety, trigger and stock design of the pre-64 Model 70, plus the finish, particularly that of the ones made in the 50's and earlier, put it in a class by itself. It is the action which everyone else tries to copy, the Rifleman's Rifle.