MTs 21-12 (known as MC 21-12 in export grade; Russian МЦ 21-12) is a Soviet/Russian recoil operated semi auto shotgun. It was designed in TsKIB SOO and manufactured mostly by TOZ; over 300,000 were produced. In fact, there were two completely different variants of the MTs-21: order-made highest-quality from TsKIB, and serial production from TOZ. The first was distinguished by the highest quality of execution, and was available in various grades, with various furniture and safety selector variations. The second from TOZ was the exact opposite; being the cheapest semi-automatic shotgun in the USSR and Russia (especially compared to order-made and imported shotguns), it also had a correspondingly low quality control and received the status of an unreliable shotgun. The TsKIB version of MTs 21 was produced in small numbers from 1956 until at least 1980s, and chambered was for 12, 16 and 20 gauge (the last two calibers were available at least until 1965), while the main production TOZ's version MTs 21-12 from 1965 was chambered only for 12/70 cartridges.
