If you can give some more details on the pistol, I have some friends who are very knowledgeable on the M1911 and A1.
Is it U.S. made? Military or civilian model, if you can tell?
Original finish? If so, blued, parkerized, or ??
Who was the maker?
What serial no. range (replace last few digits with X's for privacy if posting the info.)
Where exactly does the MB show up on the pistol, frame, or slide?
If the above is confusing, just post any and all writing that you find on the gun.
Need more info because "MB" isn't on my list of military inspectors for the U.S. M1911A1, at any of the contractors that made them.
A picture of the gun and the marking might help, but above info should help a lot.
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