Historic tie tac with marks who made it?

[jcm]

Hi,Found this unique tie-tac today marked on the back sterling with a makers mark(I believe it is) Upon reading about the company on the pin they are control data corporation they invented and manufactured the first computers for the military during WWII, unique story.
http://en.wikipedia.org/wiki/Control_Data_Corporation
anyways looking for some input about the marks
It is a sheild with an M in it (found similar ones but no this one)
take a look


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