7.92mm x 57 bullet ID help

Pulled the bullet on this 7.92mm x 57 round, and saw what looks like a metal peg has been put in a hole in the side, any ideas ?

The bullet takes a magnet along it’s length and weighs 157.4 grains.

The cartridge headstamp is P120 S* 17 39 and the primer annulus is black.

This is a “PmK” projectile, an “API-Smoke Tracer” with a white phosphorous (WP) load. The soldered hole in the side is on purpose. The solder is supposed to melt from friction heat while passing the barrel and set the WP free outside the barrel which is producing a smoke trace on it’s way to the target.


Thanks for the info, so the black annulus is what indicates APT ?

Yes, the black annulus indicates a PmK. this cartridge can be confused by overall cartridge weight and color of primer seal with Type S Ball, but the bullet ogive on the Type S Ball projectile is totally different. The PmK is one of the “sharpest” ogives of any of the German spitzer-shaped projectiles.

Jon’s advice not to poke at the plug in the hole is well-taken. The contents can ignite on contact with the air.

the black annulus indicate in WWII a chemical Filling (see also B - Gescho

The black primer seal by intself indicates a PmK. To identify a B-Patrone, which is another form of incendiary round and was at least initially classified by the Germans as a form of Ubungspatrone (practice cartridge) although it was used tactically, the black primer seal must be accompanied by the tip of the projectile being plain gilding metal and the lower 3/4 (approximately) of the projectile being chemically blackened, depending on when made. Early Beobachtungspatronen had a chrome tip along with a black primer seal. In both the early and late B-Patrone, the tip color or lack of color was about 10mm long by regulation, but in practice, these vary quite a bit. Of course, we are talking only of the German versions here.

Curious as to the process loading the WP in the projectile. Is this done in a vacuum? Inert (other) gas chamber?

I assume that it is getting done in an inert gas filled environment or in frozen/cooled condition.

Be careful, don

NOTE the 'l

Armourer, you also can take a look at this (beautiful) website:

Your bullet:
P120 S*17 39 Rfg.schwarz PmK

-Rfg.schwarz- means:
Rfg. = Ringfuge = Annulus
Schwarz = black