Good question. It was certainly used on brass cartridges loaded back in the late 1800's as a sort of half star crimp in the form of a taper used to hold the top wad in place. I have seen in in slightly later brass cartridges as a full crimp and also in aluminium ones of Belgian origin. I don't think it appeared in the U.K. in relation to paper until sometime in the 1950's where it was first used on the 1 ounce Eley 'Impax' game load. Lagopus.....