New to me 5.56x45 headstamp

While out at the range today I picked up two 5.56x45 cases with a headstamp I have never seen before.
Brass case , boxer primed, 5.56x45 (aka .223 Remington) with the following headstamp: I.M.G. II-LXXXIII 5.56
I assume the markings are Roman Numerals indicating “2 (Feb) 83”, but who is IMG?

Guatemala, on Israeli machinery, I believe.

Industrias Militares de Guatamala. There have been several forms of this headstamp.

I’ve been told that the machinery was set up by Winchester. Anybody have a definitive answer?


Thanks for the replies!
The annealing on the cases do look like tha annealing discoloration seen on Winchester cases.
The primer is plain brass in color and is not crimped into place, the case mouth crimp is of the “factory crimp” style.
From the markings left inside the case mouth, the bullet had a knurled cannelure.
Did I get the year of manufacture correct?

Gregg - yes, you interpreted the date correctly. Why they put it in Roman Numerals is beyond me!

The fine book “The History and Development of the M16 Rifle and Its Cartridge,” by David R. Hughes, published in 1990, page 191, indicates that the primary supplier of the machine to Industrias Militares de Guatamala was the German firm of Maschinenfabrik Elisenh

John, your post sparked a memory of this topic. I think that later production was done on Winchester supplied machinery after the original set-up proved to be problematic for some reason.