the American has a standard 3/8" dovetail, not the 11mm of the other CZs.
Tim,
The 452/453 Varmint in .22WMR and .17HMR also have a 3/8" dovetail. Also, the 452 FS in all offered chamberings has the 3/8" dovetail.
I doubt that anyone ever blamed CZ for making things simple.
Here's a copy & Paste from their 2009 Catalog:
DOVETAIL SIZES BY MODEL AND CALIBER
Model/Caliber .22 LR .22 WMR .17 Mach 2 .17 HMRCZ 452/453 American 3/8" 3/8" 3/8" 3/8"
CZ 452/453 Varmint 11mm 3/8" 11mm 3/8"
CZ 452 Scout 11mm NA NA NA
CZ 452 Lux 11mm 11mm NA NA
CZ 452 FS 3/8” 3/8” NA 3/8”
CZ 452 Trainer 11mm NA NA NA
CZ 452 Style 11mm NA NA NA
CZ 452 Silhouette 11mm NA NA NA
CZ 513 Basic 11mm NA NA NA
EDIT: Just to confuse things a little more, it appears, for example, that in the 2007 CZ catalog, the 452 FS is depicted as having the 11mm Dovetail. I'm starting to think that one might not ever know what your going to get in terms of a dovetail on a 452 until you actually measure it yourself.
EDIT: In case anyone is interested in the proper way to measure the Dovetail on a CZ 452, here is a very good explanation with pictures from Sword Bearer over at Rimfire Central:
http://rimfirecentral.com/forums/showthread.php?t=295503