Question: What are smaller variants of the Israeli submachine guns that copied the MCEM-2's combine wrap-around bolt and magazine in pistol grip considered to be?

A weapon with a telescoping bolt (also known as an overhung bolt) is one with a bolt which telescopes over, that is, wraps around and past, the breech end of the barrel.  This feature reduces the required length of a weapon such as a submachine gun significantly, and it allows rifle designs to be balanced around the pistol grip in a way that gives "pointability" similar to a pistol's. <SEP>  The Uzi was one of the first weapons to use a telescoping bolt design which allows the magazine to be housed in the pistol grip for a shorter weapon. The Uzi (Hebrew: עוזי‎ , officially cased as UZI) is a family of Israeli open-bolt, blowback-operated submachine guns. Smaller variants are considered to be machine pistols. <SEP>  23, Israeli Uzi and a great number of other submachine guns.  MCEM-2 was the second prototype in a line of experimental submachine guns, designed in Britain in 1944.  It was envisioned as a possible replacement for the STEN submachine gun then in service. MCEM-2 (Machine Carbine Experimental Model 2) submachine gun was produced only in prototype form, but was one of the very first submachine guns to combine wrap-around bolt and magazine in pistol grip, features later copied in the Czechoslovak Sa vz.  The MCEM-2 was developed by Jerzy Podsedkowski, a Polish constructor involved in work on Vis and Mors, who fled from occupied Poland to Britain.  It is believed that prototypes of MCEM-2 were made before the end of WW2, and its derivatives MCEM-4 and MCEM-6 were tested soon after the war.  The latter modifications differed mostly in adoption of the rate-reducing mechanism, incorporated into trigger unit; the rate of fire therefore was decreased from 1000 to more realistic 600 rounds per minute.  Nevertheless, neither prototype was found suitable for adoption, and several years later British army adopted a more conventional submachine gun, the Sterling-Patchett. <SEP> The Arsenal M23 submachine gun (Estonian: "Arsenali püstolkuulipilduja" ) (also known as Arsenal Tallinn) was an Estonian submachine gun from 1926 through 1935.  These submachine guns were designed and produced in the Estonian military equipment factory "Arsenal" in Karjamaa, Tallinn, but production was not more than 600 units.  The weapon was chambered for the 9x20 mm semi-rimmed Browning cartridge to be compatible with ammunition for the Browning FN M1903 pistol which had been adopted by the Estonian Army.  It operated on the blowback system and was essentially similar to the MP18.1; having a wooden stock, slotted barrel jacket, and horizontal left side magazine feed.  A uniquely slender 40 round single column box magazine led to frequent cartridge feeding problems; and cooling fins which were machined lengthwise along the barrel to promote cooling air flow when firing (similar to the Lewis machine gun), unnecessarily complicated production.  It was used by the combat support units of the Border Guard, the Estonian Defence League and the Estonian Defence Forces.  The Arsenal submachine gun was replaced in Estonian service by the Finnish Suomi KP/-31 submachine gun in 1938.  The Estonian Army sold a few samples to Latvia and all of the remainder found their way to Republican forces during the Civil War in Spain.