I've tried 62 and 65 gr, as well as 75 and I think I even made up 20 80's. It was someone else that suggested trying 35's or 40s, but yeah, might look at handing it in to be checked over, any idea who does CZ warranty in Canada?
Mine wouldn't shoot 60+ worth sh!t. 1-12" twist. Try 55's or 50's.