Correction, all Brno rimfires up to the late 60's have 16mm rails. 70's era BRNO's have 11mm rails same as Czs. The ZKW 465 and CZ 527 also use a 16mm rail although it appears to be a slightly different shape on top. The larger centre fire actions use a 19mm rail.
X10 on ordering from Denny. I have dealt with him numerous times. He is the go to guy for all things Brno.