Abstract
One part of universal tendencies that are connected with armament building now is orientated to creating new models of small arms, that have increased battle effectiveness. The grouping is one of the most important technical characterizations that increase battle effectiveness of small arms. In many cases, adding muzzle devices increases bullet dispersing. In order to avoid this, it is necessary that the grouping in these cases should be investigated. This article presents an experimental investigation on the influence of an additional mounted on barrel edge concentrated mass over the grouping of gunshot hits in single shooting.