Thomas,
I did some additional research on the magazines for Lugers, delivered by Mauser for the Dutch Navy. Examination of some Navy Lugers from fellow - collectors here, and reading the history of magazine - problems the Navy had with the wooden - base magazines between 1929 and 1936 I strongly believe that the following occurred:
1. From the first lot on (1928 - 77 pistols from DWM) the Dutch Navy received the magazines as they were issued in Germany for the P08, with the exception of the base. Germany used aluminium bases as from 1926, the Dutch Navy insisted on keeping the wooden base as the standard. Three magazines were send with each pistol.
2. After the first essential contracts made by Mauser were received (1930-1931), it showed out that there was a severe problem of reloading. After the first shot, frequently the second cardridge failed to feed. August Weiss reported this later, and also that the first batch of Mauser Lugers went back to Germany, were no failures could be found. The pistols were send again to Holland, but the same malfunctions persisted. Mr. Weiss went to the Netherlands, and he found out that the special way of shooting of the Navy (with a fully stretched arm) was the cause of the problems. In holding the pistol this way, the breech opened and closed faster.
3. During 1935 reportedly a solution was found. The authorities ordered five "improved" magazines for testing. Reconstruction of facts make believe, that this improved magazine was the new Haenel magazine.
4. The first time that the use of the new magazine is mentioned, is in the contract for the delivery of Navy Lugers in 1939 (225) and 1940 (1,000), the pistols were to be delivered without magazine, which might then have been ordered separetely from Haenel. (The last batch of 1940 was confiscated by the German army at the start of WWII).
5. I found four Dutch Navy Lugers at collectors here, they are all from contracts before 1939, two have a nickled body, two a bleued body and all have a wooden base, two with matching SN#'s.
I therefore strongly believe, that the 225 pistols of the 1939 contract were issued to the Dutch Navy, with a socalled "extruded" Haenel, ordered directly from Suhl, without a SN#, with an aluminium base. I do not believe that there is any acceptance stamp.
(Information can be found on pages 215 - 218 "The Dutch Luger" - Martens & de Vries").
Good Luck!