Equipment only reveals its full effectiveness if it is properly mastered. In a military context, performance is a key objective, which is why it is important to understand the conditions for successful mastery. Through interviews with combatants focusing on a specific piece of equipment, the author highlights three elements: intensive practice leading to the in corporation of the object, believing in one’s equipment, and loving it. These conditions also facilitate alternative uses, thereby expanding the range of possibilities for using the artifact . Conversely, shortened training, excessive standardi z ation and an equipment that leaves little room for the user’s creativity can restrict mastery. Finally, the culture in which the user is immersed can encourage or hinder diversion of uses, depending on the degree of conformity or passivity required of the combatants.