It doesn't look re-blued to me. Very late war production and perhaps finished in March 1945 and not issued to GermanArmy. Highest serial number reported is 87,685a. So you are in the middle of 1945 production. One would expect to see more German Army stampings, but it was near the end and stuff moved out fast. They had a mix of Kreigsmodell wood on hand, so your wood could be correct. Nice find.