Sorry for posting about a non-Mauser made gun but thought I had the best chance of finding the answer here.

First: Do the double square bridge versions of the BRNO 21 and Zg47 use the same rings as the current CZ 550?

Second: Most of the Mod 21's I see have a round action and safety on the left side of the bolt. Recently I have seen two model M21 small ring guns, both dated 1951 with a ZG47 type safety and double bridge, they both had shotgun type trigger guards and double set triggers. Is this a common varation or something scarce?

Thanks for your help