I bought mine new about a year ago. I e-mailed cz-usa about the bore size, and they replied that it should be .223. You reminded me that I've never slugged the bore, so I did. It seems that my rifle's bore is .2235, right in between. So far, I've gotten good results with .223 40gr Sierra Hornet SPs and both 35 and 40gr Hornady VMax bullets. which are supposed to be .224. I only have a 50 yd range, but here's what I've found to be promising in my 527 Lux. I'm still trying loads.
5 shot groups:
40gr VMax, AA1680 12.7gr, Rem cases, WSR primer .451"
40gr VMax, Lil'Gun 13.4gr, Rem Cases, WSR primer, .298"
35gr VMax, AA1680 12.7gr, Win Cases, WSR primer, .312"
Sierra 40gr Hornet (.223), AA1680 12.7gr, Win Cases, WSR primer .412" (4 shots in .243")
I'm trying to work up a 45grain lead gas check load that clocks about 2000fps. This would duplicate, or do a little better than .22 mag loads. I'd like to hunt small edible game and not tear up too much meat. So far the best I've managed is .941 at 50 yd. Do you know of an accurate lead bullet load?
I know what you mean about waiting until it warms up a bit to do more shooting. It was -11F this morning and eventually only got up to +15. The groups in the attachment were shot last Saturday when it briefly got up a degree or two above freezing.