All Buffalo Bore Heavy 40 Smith and Wesson +P loads use flash suppressed powders that give high velocities at low pressures. Since over 90% of all human shootings in the USA happen in low light, we believe that flash suppressed powders are a potential life-saving advantage - you don't want to be blind after you fire one shot in a life-threatening, high-stress situation. There is such a variety of 40 Smith and Wesson pistols in public use that we will not determine what pistols are compatible with which 40 Smith and Wesson +P loads - this is your responsibility. We will add that this ammo is safe in pistols that use a fully supported chamber. Please read the safety notices below. The first one is taken from the Speer #13 loading manual. The second is taken from Hodgdons #27 loading manual.