I had a similar issue with a CZ 455 varmint I purchased earlier this year.
My first few trips to the range I had mixed results. Sometimes a nice tight group
with a couple fliers and sometimes just fliers. I tried Federal AE and blue box bulk
ammo tried a couple different CCI offerings with the same results.
I thought it might improve with use and after a couple hundred rounds there is
no change other than the trigger is a lot better.
After another disappointing range trip I stripped it down and gave it a good
cleaning removed the barrel and cleaned and inspected the bore.
The rifling and the chamber look good but when I inspected the crown I saw
what looked like someone tried to de-burred the crown after machining it with an
abrasive stone in a die grinder. The rifling is ground into the bore about .010"
on one side and .030" on the other. I think I found the problem.
I re-crowned it. A recessed 11 degree target crown. Took it to the range and
put 150 rounds through it. A big improvement! It now consistently shoots
under an inch at 50 yards with the occasional flier.
Budget ammo is probably the reason for the fliers now, I get similar results
with my other .22s. You should not have to do this with a new rifle.
A lack of quality control obviously.
Terry