The PA numbers are the real numbers to look for followed by bolt action barrel, the nosecap is good if matching but ok if not there or barred out sometimes wrong number is there. Barrel dates if it matches the action date is good but if it is an early action still with an early date the Q is why hasent it been used ( two WWs plus Korea etc). If somebody tried to sell me a 1913 No1 Mk3 mint Lithgowicon unblemished i would look and walk there is no such beast. 1945 or 1953 No1 Mk3* i would look very hard at and maybe buy maybe. The more used with the right stamps and not cleaned the less likely hood of foul fiddling the more interest from me. These are battle rifles used and abused plain and simple not display pieces. Lithgow never numberd mags. There was only 640k rifles made so repairs were required thats why sight numbers are what they are, history of that sight. A rifle may have been repaired many times but never FTRd.