Cartridge 25 Pr Super is contained in a cartridge case and has a fixed amount of propellant and is kept in place by a closing cup which is shellacked in position and not removable. This particular Super is early enough to have contained WM propellant, hence the WM symbol 'N' in the square. It was used for either firing at the longest ranges, accuracy being obtained only by elevation, or with AP shot in the direct line of sight fire role. For particularly well armoured targets, there was a Supercharge Increment which was a small circular bag of Propellant WM 017 just small enough to fit loosely inside the shellacked cup. This increment was only for use with AP shot.
Normal cartridges which contained a Red, White and Blue charge bag, achieved their distance and elevation by removing the necessary bag(s) according to the zone required.
The package was used for Cannister's at a much later date, as indicated by the UN Code 0303. This system did not appear until the late 1960s early 70s. This particular code means " AMMUNITION SMOKE, with or without burster, propellant or propelling charge".
