[lugerholsterrepair]

Jack, I have to admire persistence but many books contain errors and this one is no exception. The statement that stocks after 1910 were fitted with brass discs should tell you all you need to know about this mistake. This statement is clearly not the case as 99.9% of stock discs as we know, are steel. Let us consider that PERHAPS some tiny percentage of original Navy Imperial stocks did have a brass disc. That's OK with me because I have learned to never say never. Putting that aside..for now we backtrack to the other characteristics of your stock that literally scream NOT ORIGINAL. There is no accounting for those and in total the whole comes together as an impossibility, brass discs or no.
Errors like this in famous books written by famous people misinform and lead us astray..but rest assured Herr Gortz knows that all discs in all stocks after 1910 were not and are not brass and that is what this statement of error indicates. Likely a translation mistake from German to English. Nothing more.