Where do you have this info from? Just curious as I'd like to know more. My understanding was that Zastava has been using the same original Mauser based design just like CZ. Their modernized versions may have changed slightly but the receivers have not changed much in the front end area so I assumed the Zastavas retained the C just like the CZs but I have never seen Zastava action alone. Maybe I should take my Whitworth apart completely.Santa Barbara are actually "truer" Mauser actions than Zastava because they retain the C-collar in the front bridge. This deflects gases better in case of a rupture case than the Zastava internal collar cut on both sides.