I own a CZ 550 in 6.5x55. It is one great rifle! I have had zero problems with winchester brass. I plan to buy some Lapua brass soon (I imagine the CZ being a euro. rifle it should handle the standard .479 case head). My 2 cents.

I have 3 old Swedish M96 mausers that digest whatever you put in them. However I became intrigued with the 6.5x55 and got a Remington Classic in that caliber. It also will digest anything but I only feed it Lapua cases, and Lapua 108, 123 and 139gr. Scenar bullets. The accuracy with VihtaVouri powders is teriffic. The Lapua brass differs a bit dimensionally from the American cases. Length is slightly different as is head size. Trimming and neck sizing usually iron out any problems you might encounter. I would expect the CZ to be more in line with Lapua reloading products, but I'm not certain. Best wishes.

Cal - Montreal

I had a 6.5x55 built on a push feed M70 and it worked well with Lapua brass but Norma brass was very tight in the bolt face. The 6.5x55 I had built on a controlled feed M70 worked fine with the Lapua. I never tried Norma brass in it.
Didn't modify the bolt-face on either action.
Strangely, my Remmy 700 bolt face had to be modified to fit Lapua cases. Good shooting