I may be wrong here, but I understand the practice continued till about 1916. Thereafter the stock discs were blank, because (or so I have heard) this information gave the enemy potentially useful intelligence. Most discs on SMLEs are thus blank. In the Boer War (and earlier) similar info is to be found on brass buttplate tang or (in the case of .303s Martinis, Lee Enfield carbines, etc) on brass stock discs.