In previous posts (see Oh K), I have called this design French Clarendon XX Condensed. While the design is without a doubt a French Clarendon, the Hamilton Manufacturing Company, the maker of this font, called it No. 95.
The capital K posted on January 16 had a crude abbreviation cut into the foot of the block. Surprisingly, this capital M seems to have been a previous attempt at an ad hoc August abbreviation. Notice the multiple starter holes created by a drill or drill press. A shocking amount of work was completed before the realization that the right-reading letters would not work for a relief printing process.