The STM-545 and STM-415 semi-automatic carbines are manufactured by the Soyz-TM company from St. Petersburg, Russia. Both carbines are evolutionary developments of the AR-15 style rifles, also produced by the Soyz-TM for domestic commercial market, and are appropriately modified for use with Russian 5.45x39mm ammunition.
STM-545 Competition carbine, a high-end gun for IPSC and 3-Gun matches
The STM-545 carbine was originally devised as a high-end “race” gun for practical shooting under IPSC rules, but it also can be used for hunting small game. The STM-545 carbines already helped some of its owners to win Russian IPSC national championships.
The STM-415 carbine, on the other hand, was originally designed to be used in “tactical” shooting matches, held among some Russian “Spetsnaz” Military and LE units. Originally, these matches were shot with standard issue 5.45mm rifles, usually highly modified and customized AK-74M or AK-12. In those matches IPSC-style or tactical dynamic shooting is combined with various obstacle courses, where guns could be used in simulated “combat style” environments with lots of dust, sand, snow, rain and other natural or artificial elements that might impede normal reliability of a conventional sport-tuned rifle.
STM-415 carbine, a “tactical” variant for use under harsh conditions
Both variants are built on a traditional AR-15 platform, but with certain specific modifications. The most important departure from a “mil-spec” AR-15 platform is an entirely new, proprietary magazine specifically designed to work with 5.45x39mm ammunition, which is slightly fatter and has more case taper than a 5.56mm/.223 Rem ammunition, “native” to the AR-15 platform. This proprietary magazine looks like a slightly enlarged (longer and thicker) polymer “STANAG” magazine, and woul not fit into a STANAG magwell. A STANAG magazine would be too small for an STM-545 magwell and would nod work in this rifle. New magazine ensures reliable feeding of all 30 rounds, as well as optimal feeding angle from magazine to the chamber, which allows for minimal friction and improves reliability with “tuned-down” gas systems and lightweight bolt carriers, typical for the high-end “race” guns. This magazine also allows use of an AR-15 style bolt hold-open device.
The 30-round Soyuz-TM magazine for 5.45x39mm ammunition (green) compared to the typical 30-round STANAG magazine for 5.56x45mm/223Rem ammunition (black)
STM-545 carbine is usually made with an 18” barrel, equipped with a rifle-length DI gas system, which is considered to be the best for its intended sport use.
Close-up view to the hybrid gas system of a STM-415 carbine
STM-545 carbine is usually made with a 415mm (16.3”) barrel, same length as used in military issue Kalashnikov AK-74 and AK-12 rifles. To ensure high reliability under the “combat style” conditions and maximum possible accuracy, STM-545 carbine is equipped with a patented hybrid gas system, which puts a short length of a stainless steel gas tube between the gas block and the gas cylinder. The gas cylinder is affixed to the upper receiver, to avoid a negative effect of the short-stroke piston system on the barrel vibrations, and thus reduce vertical dispersion. Both DI and Hybrid systems feature a manual gas regulator. Also, both STM-545 and STM-415 carbines use cold-hammer forged and chrome-lined barrels, which work best with Russian steel-cased and steel-jacketed ammunition. Barrels are threaded to accept various muzzle devices.
Both weapons can be ordered with a fixed or a telescoped stock, various forends and other furniture.
Encyclopedia of firearms and ammunition of the XX and XXI centuries
All texts are written by Maxim Popenker © 1999-2025
