Data I've seen is for a 24 inch barrel.
The CZ FS has a 20.5 inch barrel, 3.5 inches shorter.
One thing about larger bores, they tend to lose less speed per inch
of barrel than smaller calibers do.
In theory, I'd say you would not lose more than 100 feet per second
as opposed to a 24 inch barrel. That's figuring 25 feet per second
per inch. ( 87.5 fps according to the math. )
In reality, you could take two rifles with the same barrel
length, and see more variation than that between the two.
So for all practical purposes, I think it's no big deal in this instance.
Even if we double that estimate ( 50 fps per inch ), you're looking
at 175 feet per second tops.
Now, it is also known that there are "fast" barrels, and "slow"
barrels, so the end result is really a crap shoot.
That's the best I can tell you.