The CZ Model 25 (properly, vz.48b or Sa 25 (samopal vzor 48 vÃ½sadkovÃ½ ... submachine gun Model of the year 1948 para)) is generally considered the best known of a quality series of Czechoslovak designed submachine guns manufactured and introduced in 1948.
There were four somewhat very similar submachine guns in this family: the Sa 23, Sa 24, Sa 25, and Sa 26. The primary designer of the submachine gun was Vaclav Holek.
The Sa 23 series utilizes a straightforwards blowback action, the weapon has no locked breech, and fires directly from the open bolt position. The submachine guns also use a progressive trigger for selecting between fully automatic fire and semi-automatic fire. Lightly pulling on the trigger will fire a single shot from the weapon. Pulling the trigger further to the rear in a continuous non stop motion will fire fully automatically, until the trigger is released or the magazine is emptied.
The Sa 23 series of guns were the first production-model submachine guns with a unique telescoping bolt, during which the forwards part of the moving bolt extends forwards past the back end of the barrel, wrapping around that barrel. This novel feature reduces the required length of the submachine gun drastically and allows for better handling and balance. Handling of the weapon was further improved by using a single vertical handgrip where the ammunition is housed and trigger mechanism, roughly centered along the gun's length. The submachine gun's receiver was machined from a single circular steel tube.
The design of the Sa 23 family of submachine guns is most notable in the west for having been the inspiration of the slightly later Uzi submachine gun.
* The Sa 23 (vz.48a) was the first variant, using a fixed wood stock and firing standard 9 mm Luger Parabellum (aka 9 mm or 9x19) ammunition. Has a straight vertical pistol grip and ammunition magazine. Magazines were issued with 24 and 40 round capacity.
* The Sa 25 (vz.48b) was the second and perhaps best known variant, using a folding metal stock, still firing 9x19 ammunition. Other than the folding stock, is identical to the Sa 23 and uses the same 24 and 40 round magazines.
The Sa 24 and Sa 26 were introduced after Czechoslovakia joined the Warsaw Pact, and were redesigned to fire 7.62x25 mm standard Soviet type pistol ammunition.
* The Sa 24 (vz.48/51a) corresponds to the Sa 23, using a fixed wood stock and firing 7.62x25 ammunition. Can be visually distinguished from Sa 23 as it has a slightly forwards-slanted pistol grip and ammunition magazine, though the main receiver and other components are otherwise visibly identical. Was issued with 32 round magazines.
* The Sa 26 (vz.48/51b) corresponds to the Sa 25, with a folding metal stock but otherwise identical to the Sa 24, using the same 32 round magazines.
After the Sa 25 was declared obsolete and terminated in 1968, many of the 9 mm weapons were continuously sold around the world. The surplus weapons were exported to other gun seeking communist countries including North Vietnam. Interestingly, a somewhat-modified variant of the 9x19 model was produced in Rhodesia in the early 1970s and termed the LDP. Manufacture of the weapon was later transferred to South Africa where it was briefly sold as the Sanna 77 in semi-automatic fire only, for use and sale by white farmers as protection during the country's internal difficulties.