Powder as propulsion powder or ignition powder for accelerating projectiles for mortar systems is based on nitrocellulose and comprises a crystalline, nitramine-based energetic material at 1-30 wt % and an inorganic muzzle flash suppressor at 0.1-10 wt %. The powder is in the form of grains, and the grains on their surface optionally have an inert plasticizing additive at not more than 1 wt %. The crystalline, nitramine-based energetic material is preferably at least one compound from the group encompassing hexogen (RDX) and octogen (HMX). The inorganic muzzle flash suppressor preferably comprises at least one compound from the group encompassing potassium nitrate and potassium sulfate.