I finally bought one of these a few weeks ago. I was searching all over for info on the web without much success, so here are a few things I've discovered.
For ammo, I have shot the 165 gr GMX, 180 gr Hornady SP, 150 Barnes TTSX, PRVI 180 gr, and 200 gr DRT. I bought a few other boxes but haven't shot yet. I've only shot on a lead sled with a good wind, so not ideal conditions and I'm no benchrest shooter. 3 shot groups at 100 yards.
The GMX is the odd one out, it shoots all over the map, 3" or 4" groups. The Hornady, PRVI, and DRT are all a hair over 1". If 180 grains are bullseye at 100, the 165 are an inch or so higher, and the 200 gr are 2-3" lower. The Barnes TTSX are the best shooters so far, just a bit over 1/2". That works perfectly for me as the Barnes TSX is by far my favorite hunting bullet and the 150gr is very flat shooting. So I plan to stick to that.
This is my 3rd CZ 550 and the trigger has a lot of creep. I know how easy it is to adjust the trigger but you have to pull it out of the stock to do so and this UHR rifle has the cross bolts so I haven't done it yet, not sure what is involved without checking the manual. But the set trigger is perfect so no rush to adjust the trigger yet.
The last nit is the scope mount. It is very high. I like the idea of the 1 piece base but wish it were lower. I guess it is because the bolt throw is so high that the height is needed to clear the scope? I'm using medium Warne QD with a 30mm Swarovski on my CZ 550 FS 6.5 and the bolt just barely clears the scope.
On this UHR I'm using a 30mm Leica 3.5-14 scope and the rings don't fit that well - I have the same issue someone commented on at the CZ-usa website - the supplied screws only get a minimal amount of thread into the base. I solved that problem by ordering 18-40 screws from Brownells but it is stupid to have to do that.
Other than that it is as expected. It is not light but not overly heavy. The stock grip is much fatter than the CZ 500 FS but about the same as my regular 550 American. I like the barrel contour - not a varmint but not too whippy that it heats up and sprays bullets like my old 7mm Sako this is replacing. As long as the TTSX keep grouping well under 1" I will be very happy with this gun.