AVT-40 automatic rifle was accepted to manufacturing in May of 1942 and the first weapons came out of production line already in July of the same year. The reason allowing advance as fast as this was rather simple - the changes required for making SVT-40 select-fire automatic were only minor. Only real changes happened in trigger mechanism. While in SVT-40 the safety switch had only two settings - (semi auto) fire and safe, in AVT-40 the switch had also full auto setting for automatic fire. However, likely AVT-40 were used mostly in semi auto mode, as full automatic fire was quite difficult to control and durability proved to be an issue. All the reliability issues of SVT-40 were still included to the design and now the automatic fire caused additional problems. The main visual difference between SVT-40 and AVT-40 is in their muzzle brakes. Muzzle brake of AVT-40 has only 4 large vents - 2 in each side. In addition new stronger stock version was manufactured for AVT-40. Sometimes AVT-40 muzzle brakes and/or AVT-40 stocks can be found in SVT-40 rifles, but these might be results of later repairs and arsenal refurb work. The Soviets stopped manufacturing of AVT-40 in summer of 1943.