i just picked up a cz 550 lux .243 in january. im very happy with the fit and feel of the rifle but i havent been able to get a good load going for it yet. i havent exactly fired many loads but thus far ive used a barnes 62 varmit grenade with vihtavuori n550 from 40, 41, 42 and 43 grains also being loaded to 0.005, 0.010 and 0.015 off lands. ive also used n150 in 43, 44 and 45 grains at 0.010 off lands. the other bullet i used was the sierra blitz 80 grain with n150 in 35, 36 and 37 grains loaded to 0.005, 0.002, 0.010 and 0.015 off lands. the best so far has been 42 grains of n550 with the varmit grenade to 0.005 off lands yielding about 1 1/4 inch groups at 100.
i also tried some heavier deer hunting bullets but i put them on hold till i can get a good crow/varmit bullet going. a hornady 100 innerlock was actually very promising with just under moa in the only load i tried.
ive also got a bunch more loads loaded up in 58 v-max, 87 v-max, more blitz loads, more varmit grenade loads and a few others that i cant remember right now. the rifle has barely been shot so it might break in a little further. it is at least super consistent over the chrony.
all the load developement aside the rifle is great after a little bit of elbow grease. i bypassed the set option in the trigger and what i was left with is something that can rival the 40x trigger on my remy 700. with the guidance from a gunmith i used to work with, i was able to increase the extractor tension on the bolt making it much quieter to operate. i also beveled the magazine retention latch a little bit more so the mag just slips into the rifle with a positive snap. i polished over the bolt raceways making the bolt smoother to operate then most sako's. my gunsmith also polished the safety detents to make the operation of the safety latch quieter. he also touched up the checkering so that it doesnt look laser or machine cut like most others. the rifle after all this work feels like nothing that you could ever pull off the shelf. it may say cz on the side of the rifle but it defines what a true sporting mauser should be.