IMR 7828 SSC Smokeless Gun Powder For Sale. The production of IMR powders stretches back more than 200 years, when E.I. DuPont started the enterprise. Reloaders all around the world rely on the IMR range of powder, which is compatible with a variety of reloading applications. IMR 7828 SSC magnum rifle powder has the same burn rate and utilizes the same data as ordinary IMR 7828. IMR 7828 SSC Smokeless Gun Powder For Sale.  However, because of the very short kernels, metering is almost as accurate as with a spherical powder. This provides up to 4% extra powder room in the case and in many situations results in more velocity than the regular 7828. In the data, such loads are denoted with an asterisk to indicate where standard 7828 would not fit.