Textbook Of Small Arms, 1904
“ After breeching up, the body and barrel, the bolt and bolt-head are assembled with their components, and sent to be proved by the inspection department, after the body, barrel, sight leaf and bolt have been stamped with the same number…..the body, barrel and bolt-head are marked with the proof mark, and the barrel with the view mark and date.
The viewer’s mark consists of a number below a crown, the letters E or B are also put on to denote the place of manufacture. The marks are placed on the left side of the body, and on the left side of the barrel close to the junction of the barrel and body.
Private rifles or carbines that have been submitted for a modified inspection to the Small Arms Inspection Department after they have been finished and are found to be in general conformity with Service patterns, so that they may be used in matches restricted to rifles or carbines of Government pattern, are marked with the above marks on the right side instead of on the left.”