A problem I encountered with my maxim - was excessive headspace.  The Germans, in their ultimate wisdom, thought their machining prowess so superior, that no headspace adjustment was needed on their guns.  So, in order to change the headspace on your 80+ year old German Maxim, you must scour the earth for barrels, locks and barrel extensions (read: PRICEY!).   After discussions with many people, those who I have previously mentioned (Bob Naess, Omega Arms, Allegheny Arsenal, the maxim List serv) I ordered a lock from Bob Naess.  After looking at it, over a few Beers, I had a bright idea... can a russian lock be hybridized with the german one??

I measured the width of the extractor on both locks, and determined that the only difference was the lifting arm region of the extractor.  On the MG 08 lock there is a second, lower, engagement area.  This is not present on the Russian locks, and actually interferes with the russian lifting arm (see above pic).  I Measured the distance from the extractor ears to the top lifting arm engagement surface of the extractor, they were the same on both guns.  I then ground off the lower lifting arm engagement surface (see below pic).  The MG 08 extractor now slips on the Russian 1910 tail end.
 
 

I had bought some T24 recoil plates from Omega Arms, in order to use the extractor springs, so i had some on hand, and the connecting "lug" is the same as the russian one (see below).  I installed the lock, to find that the lock trigger didn't engage the guns trigger bar, it was perhaps 1/8th" too short.  I brought the lock up to my boss' workshop (thanks MBD) and he did his TIG wonders, you can't even see that its been worked on!  The lock headspace is set by spinning the nut on the connecting lug on the barrel extension plates.  To maintain the set headspace either insert headspacing washers (like they are available?!) or use red lock tite.  (I bought my 8mm mauser HS gauge at brownells.com )