My CZ likes the Hornady 20 gr HP and the CCI 16 gr "Green" ammo the best. It will shoot them an inch or under at 100 yards, while the 17 gr stuff opens up to 2 or 3 inches. This is my second CZ as the first one had a headspace problem, was retunred to CZ and they replaced it with the one I currently have. The first one shot the 17 gr Hornady ammo very well and did not like the 20 gr...go figure.
I haven;t tried and 15.5 gr NTX round.
