now when the 2013 ends it comes clear that this deal never happen. while waiting for the export licence I lost contact to the seller.
meanwhile I have solve the question which ammo the rifle was made for. what we know is that the 10,75 Mas was build in 1950 probably earlier. the only ammo brand available in theory was than kynoch but I dont now when kynoch start to make this caliber again after ww2. one source says big bore ammo was rare many years after WW 2 at least outside of the empire. DWM and RWS ammo was not available before 1955 but nobody expected to see german made ammo ever again in 1950! so there was also czechoslowak made ammo but Sellier&Bellot and Považská Bystrica by Sellier&Bellot told me this caliber was available from 1957 to 1965. I dont have informations about Považská Bystrica only the ammo box come up from time to time.

post war DWM

RWS, Kynoch and Sellier&Bellot

Považská Bystrica

than I found a pic of a french ammo box, 10,75x68 on Mauser 98 clips

dont know who L.D.&Cie was, the box could be post WW2
looks clearly like a gunmaker box but you can see "chargees en france" what I would translate as loaded in france.
very possible the ammo there is in fact this:

this ammo was made after WW 2 in the french military arsenal in Toulouse. its an old trace for me because I found this before in a french cartridge collector manual

a experimental anti tank cartrige for a cone bore rifle after Gerlich made between 1950 and 1952. obviously someone in this arsenal use his postion for leting made a lot of 10,75x68 sporting ammunition, maybe a fanatical big game hunter

no doubt that this was the ammo this special rifle was build for.