For BSA and Greener rifles view complete catalogues from 1908 to the mid 1930s on our CATALOGUES PAGE As far as civilian rifles are concerned, some manufacturers have their own dating systems, with, for example, prefixes or suffixes to serial numbers providing that information.Anschutz target rifles fall into this category, and their system is given on the page for these rifles.For the latter, dates of introduction of military arms can be located within the Government "List of Changes" (Lo Cs) as can dates of obsolescence and of modification or upgrade to later marks.Basic information on these lines is on site from our .
From 1975 a further modification was made to the mark, as in Figure III, with another adjustment soon after to Figure IV.
It is to be found under the barrel just foreward of the receiver, and requires removal of the fore-end woodwork to view. It is possibly the diminutive size of this mark, and its usually hidden location, which has led to it being described as 'secret'.
In this instance, the code letter is 'M' for 1932-33, indicating that the rifle was manufacture, or at least proved, between July 1932 and June 1933. Post-War rifles such as the BSA Model 12/15 will not carry this mark.
The date code letters were thus 1975 - A; 1976 - B; 1977 - C; 1978 - D; 1979 - E; 1980 - F.
To give some idea of what you are looking for, the image below shows the mark, as Figure I, on a BSA Model 15 rifle.