Just some inf you may already know Steve. The top of the receiver is machined with a 3/8" wide dovetail groove for mounting standard rimfire dovetail rings. Not sure why the CZ rings would not fit. There are American and European ring differences.

the CZ452 had different size dovetails the 452 American had 3/8 the rest of the 22 lr 452 models ha 11 mm dovetails hope this helps link to 452 dovetail chart diproductsinc.com/Products.aspx?CAT=4268

The CZ452 had different size dovetails the 452 American had 3/8 the rest of the 22 lr 452 models ha 11 mm dovetails hope this helps link to 452 dovetail chart diproductsinc.com/Products.aspx?CAT=4268

the CZ452 had different size dovetails the 452 American had 3/8 the rest of the 22 lr 452 models ha 11 mm dovetails hope this helps link to 452 dovetail chart diproductsinc.com/Products.aspx?CAT=4268