hello,
no mention of deinstglas in any of my ajack stuff. most rifles were made in 1937-39 but seen other dates. some 4x90 commercial scopes were made before, during & after the Dienstglas scope run and before the wartime scopes, the lowest serial for wartime 4x90 is 42443 I have. ajack stopped exporting in 1940 and my catalog ONLY lists the 4x42 & 4x68 in 1939. In 1940 the 4x68 was discontinued and the NEW AJACK 4x90 was introduced. being the catalogs are printed in nov of the previous year, like catalog 1939 (printed nov/dec 1938). this also shows that the scope was around in 1939 as they would have not updated there catalog of available scopes and made changes if they were not already available when printing the 1940 catalog. which we know since the 1940 catalog was printed in nov 1939, they were obviuosly available to purchase in the commercial market. So i have always used that the AJACK 4x90 was intorduced in 1939 so has to be the same year the Dienstglas was made and manufactured. sorry i can't offer more info, info and catalogs are scarce.
later
vaughn