I.D. of .50 BMG headstamp needed


In case the image is not all that good, there is a capitol E at 12 o’clock, 2-1 at 8 o’clock and 13 at 4 o’clock.

Any chance this is WWII vintage Japanese?

Thanks for looking.



Yup, a Japanese 13.2mm round.


Thank you.

Is 13.2 Japanese and .50 BMG interchangreable? On the outside, at least, they appear to be exactly the same.



They are very similar but not interchangeable. Jack


For those not familiar with the Japanese dating system(s), it might be well to expand on what
PierreJean has written. He is correct, but it may be confusing to some.

Until 1927, there was basically only one dating system used by the Japanese military, and that
was based on the year of the era (reign) of the Emperor on the thron at the time. For example, a
Type 38 Japanese Rifle was made during the reign of Mutsohito, the Meiji Era, or in English, the “era of Enlightened Rule”). The rifle was adopted in the 38th year of Meiji which is 1905 on our calender. The
Emperor’s actual name was not used in polite company, since Japanese Emperors were considered
direct descendents of God, and themselves God-like, with the name of the era used instead. World
War II was fought during the Showa era (“era of Enlightened Peace”), the reign of Hirohito, which began in 1926 and ended with his death in the late 1980s. Weapons adopted according to the sitting Emperor’s era-year remained so designated until the end of the war, and were usually dated, if at all, by that year.

In 1927, the military began to use a second system for dating, both in model designations and the simple dating of the year of actual manufacture of items adopted under that second system. It was based on the erroneous
founding date of the the Japanese Empire, with the dates of the reigns of the early emperors incorrectly figured.
The supposed date was 660 BC, although in truth, the first Emperor of the Japanese Empire, Jimmu, did not take
the throne until about the middle of the first century AD, perhaps around 50 AD.

The shell in question is, as stated, made in 1942, the “Koki” date 2602. another example would be the Type
94 Pistol, which is designated such from the last two digits of 2594, or 1934, when the handgun was adopted.
The cartridge in question has only one number because the number that would (should) precede it is "0) (zero) and in that case is often dropped from the designation. In cases of the first number being other than zero, these dates are always used with the last two digits, not just one.

John Moss