The Czech Brno rifles and the Zastava Serbian rifles are differing breeds. No "cross pollination" I've ever heard or seen. The Mark X was a brand as noted, predominantly marketed by Interarms and Firearms International. The latter of Washington, D.C. It was a follow-on to the military rifle manufacturing capability of Yugoslavia reflected in the Military Mauser Model 48 and returned as refurbishes thereof. Such perhaps the last genre of their Model 98 in military format. Fourbore has it correct. Zastava made the commercial model as very close copy of the post WWII FN commercial action. Notably features of both, solid left sidewall and "low scope" factory bolts. Zastava survived as FN with labor costs mounting moved on to lesser commercial production. 'Petering out' in early sixties. It seems most likely that Interarms copyrighted the Trademark "Mark X", perhaps surviving Interarms/perhaps not! By now largely academic. The Zastava Mark X, by whatever name, in my estimation, not 'quite' the quality of the original post WWII FN commercial action finish. Yet close and more pointedly "competitively priced as FN pricing itself out of the US - make that world - commercial mauser market! The Zasatava is a fine rifle action and serves well in a plethora of its own and 'house brand' rifles.
The CZech early-on postwar commercial rifles, to a different drum beat! Only as first production as essentially the same military mauser style actions! By forty six/seven era, produced under the name "Brno". From initially that first production; morphed and significantly! The typical 'new age commercial mauser solid left sidewall, but more! New striker designed with yet striker impinging safety style but "low scope" considerations. The presentation completely different and by today's standards, definitely more modern. Produced in two rifle styles, half stock and full stock, as Models 21 and 22 (later 721 & 722) respectively. These to my mind the quintessence of a lightweight classic European mauser 'genre' rifle designs. The singular feature I don't care for, the stamped steel if artistic, bottom metal. Looking great but giving up some strength factors. They were marketed in America as early as 1950 to my knowledge and 'perhaps a bit before. Chamberings were yet 'meteric'. That as likely hampering US marketability. But moreso, the cooling of relations between the US and Soviet nations altogether. I 'believe' these were marketed by the firm "Continental Arms". They never made much headway here and nowadays aren't common, particularly in original 'non-tapped' format.
By latter 1950 they were superseded by a later significantly different as 'ostensibly improved' if losing a bit of that classic Euro-charm. Now branded "CZ" and with such model number nomenclature. Yet functionally mauser action, but much more akin to the rare "double square bridge Oberndorf Mausers of prewar, meant to accommodate scopes. The square topped 'new & improved' receiver ring & bridge, neatly dovetailed for integral scope mounting. CZ also returned to the forged steel bottom metal! These were great rifles, largely ahead of their time. But 'failing' as trade relations with the Soviet nations cooling materially. The Korean war in progress and The USSR supporting. A hiatus as eventually the new newer versions of the CZ rifle yet occurring. But - just my take - the referenced Brno & first CZ models reflecting the epitome of quality manufcture. Both with the solid sidewall and "low scope bold handles. Both too, such handles in likeness of the classic Steyr Mannlicher "flat spoon -kinda handles achieving handsome!
This banged together and submitted without edit. Pardon! If time, later to add pix of both Brno and Cz models referenced here.
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Beautiful classy-classic CZ rifles there Mag & fourbore!
Best!
John
