My full size B CZs absolutely love Win NATO 124gr for tightest groups. They also prefer 115 over 147 grainers from a grouping perspective. Glad my Rami likes Fed HST 147gr cuz not only my favorite SD round, but also the smallest groups through it!
That is phenominal shooting at 25yards, with iron sights, off hand. As mentioned, the gun could improve precision from 10x bushing, YOU could possibly improve with a race hammer, spring kit, optic,, rest, etc.