Mexican .45 Auto Boxes - Meaning of Initials

Below are images of two Mexican .45 Auto caliber cartridge boxes from my collection. The orange box at top dates from 1938, with cartridge headstamp " - F DE M 45 AUT - 1938 “. The red box is from 1956, with cartridge headstamp " FNM45-A* 56”.

Below them are the side labels from the two respective boxes. Note the monogram-style markings on the orange 1938 box of “EFM” enclosed in a circle, and on the red 1956 box “OIM” (Possibly “DIM”).

Can anyone tell me the meaning of these two sets of initials. I could make an educated guess, but choose not to. I would like the meaning to come from someone who knows, and not just a guess based on knowledge of the Spanish language.

Any help appreciated, of course.

John Moss

Hi John, “EFM” stand for “Establecimientos Fabriles y Aprovisionamientos Militares” (1917-1935) and “DIM” stand for “Departamento de la Industria Militar” (1947-1977).

Between those designationes it was also called “DMG”, standing for “Dirección de Materiales de Guerra” (1935-1946) and “DIM”, standing for “Dirección de Industria Militar” (1946-1947).

The head figure is called “cuāuhpilli”, the eagle warrior of the Aztec empire.

Un saludo grande,


I told a friend before I posted these box labels here, for whom I took the original pictures today, that it would be a friend from Argentina that would answer this! Gee, I wonder how I knew? :-)

The only comment I have to make is that for “EFM,” you can extend that date range at least to 1938, the year the ammunition in that box was made.

Muchisimas gracias, Fede.


Glad to help!

The date range reflect official changes, but it is evident that in 1938 they continued using boxes showing the former designation.

I thought I had a variation with the thumb cut in the “EFM” box but not. At any rate it’s also the top one in these two boxes & the lower appently completes the set. Grest stuff Fede & John.

Pete - what are the headstamp dates on the cartridges from the two boxes you show?

Fede - Thank you for the information regarding the official change of designation. I should have thought of that, as obvious, things like this don’t happen overnight. Sometimes it takes a fairly long time period to implement changes officially approved.


Unfortunately both are empty.

Pete - Thank you. That is one of the problems of empty boxes, of which likely half my box collection falls into that category. Fortunately my two boxes shown have cartridge specimens that I know to be original to the box.

John Moss