Old Casing found in Siena Italy

Found an old bullet casing in Siena Italy. The back of the bullet has P28 So Ex 39 engraved on the head stamp. I have no idea what country, weapon, or era the bullet is from?

P28 is DWM of Germany
Ex 39 is “Exerzierpatrone 39”, or “drill cartridge 39”, meaning inert practice cartridge used to test cycle the firearm for function test.
As for “so” I don’t recall its significance.

The caliber is 7,92x57 (or 7,9x57…) and would be used in guns like the MG34, MG42, K98k, ZB vz 26/30, and other guns in the same caliber


I would make one correction to Tennsats answer. The “39” is not
the Model Designation of this cartridge, but rather the date of manufacture
of the specific cartridge (remnant) that you found. The “S°” found on the
headstamp represents a brass cartridge case. Why the small “circle” was used
in lieu of the normal star figure after the “S” is not known to me.

I would add that the specific factory that made the cartridge was Deutsche Waffen und-
Munitionsfabriken A.-G., at the Karlsruhe i/Baden factory. I mention this because there
were three DWM factories making this caliber of ammunition - Karlsruhe, Berlin-Borsigwalde
and Lübeck.

The part you found is not a “bullet” but rather the remains of a cartridge. In a normal
cartridge the part you found would be the case, one of the four major components of
a cartridge, which are the case, the primer, the bullet and the powder charge. The word
“bullet” on applies to the projectile itself, not to the entire cartridge (in German, “Patrone”).

The weapon these cartridges were mostly used in was the K98k, the standard German
service rifle of WWII. Of course, they were used in similar rifles of the same caliber made
in the occupied countries, both during and before the German occupation. They could also
be used in the various machine guns used by the German Armed Forces, as well as in other,
more-limited use rifles, such as the semi-automatic G43, G41M and G41W.

They were not only used for function testing of various small arms, but also as a training device
to teach soldiers, safely, the loading, unloading and manipulation of their issue weapons.