The main difference between this model and the M2R series is a polygonal barrel made from blanks of the Izhevsk manufacturer Alfa Precision. The polygonal barrel allows firing full-bodied bullets weighing more than 3 grams, in addition, this is facilitated by a direct-flow air supply system. The branded composite flask with a volume of 0.48 liters allowed to increase the number of possible shots from one refueling. The working pressure of the bulb is 310bar, the test pressure is 375 bar. The ATAMAN MB20 model has an innovative "Delayed Shot" system, which eliminates the possibility of sending two bullets into the rifle barrel.