I am trying to determine all of the letters that were stamped into the cases of Remington-UMCs .22 short and long rim fire cartridges, just below the case mouth. I know they were used after the merger of the two companies and prior to their incorporation, as I have a box of these with the ‘S’; UMC may have used them as well prior to the merger, and they may have been used after incorporation. I believe the ‘S’ stood for smokeless. In addition, there was an ‘L’ (Lesmok), a ‘G’ (greased), and a ‘U’ (ungreased). What others were used? Also, were these limited to .22 rim fire?