A 7,92x57 box


#1

As my search for charger clips grinds almost to a halt, having found most of the easy ones, I’ve turned my attention to packaging.

At an arms fair yesterday I bought a couple of empty boxes for German 7,92x57, I’ve been buying these because they’re often marked on the label showing the contents are loaded into chargers… It’s an indication that you’re a serious collector when you buy something because it doesn’t mention what you’re interested in … it’s a sickness but not as medicine understands.

Apparently (thanks Phil) a bit of a specialised loading, I wonder how many of these were made.

Happy collecting, Peter


#2

I had already sent Peter an E-mail about this box and have a picture and text handy so I might as well post them here too.

This is a picture of the correct cartridge for this box. The green band on the bullet indicates it is a –v- (verbesserte – improved) loading. The black band at the case mouth indicates it was loaded for the tropics (auch für Tropen). The black annulus indicates it is a P.m.K. loading. Boy, the Germans sure were sticklers for details!!

Loosely translated, I guess you could call it a Armor-piercing Incendiary Hi-Velocity for Tropical (North Africa) Use loading!


#3

What was so different between North Afrika and, let’s say, south Italy or Greece, that they needed a special load?


#4

sksvlad - Dan Kent in his book “German 7,9mm Military Ammunition” goes into this subject pretty well on page 67 of the 2nd edition. It mainly has to do with the effects of high temperatures and low atmospheric humidity on ammunition performance.

Remember we are talking mostly about the Sahara Desert and nearby areas.


#5

Phil, thanks, I’ve read p.67. Kent says that high temperature and low humidity basically make gas formation inside the cartridge more “violent”, I understand how overheating inside of the cartridge may result in this, but what low humidity has to do with it? Can you explain?


#6

sksvlad – You have asked the wrong person that question. I know that temperature and humidity makes a difference but the whys and wherefores are beyond me! Those were two of the variables we had to crank into the old mechanical analog ballistic computer on the Gun Fire Control system Mk. 56 on the second ship I served on. Has anyone ever heard of a sling psychrometer? It is a device that has two thermometers mounted on it; one with a wet bulb and one with a dry bulb. You sling it around over your head for a period of time, then by using a chart and the two temperature readings you determine what the relative humidity is. I don’t know why that piece of ancient history popped into my head as I was answering the question.


#7

pbutler: I used a sling psychrometer in school; we were doing temperature/humidty studies in the woods and out in the open. That was a long time ago. I always wondered why the mercury didn’t settle down in the bottom when the thermometers were whirled around.


#8

High tempreature and Low Humidity == Increased pressure from discharge of Powder…This is due to Two factors, one the Boyle’s Law, PV over T is a constant (ie, Pressure and Volume vary inversely as the temperature; if Volume is constant and the Temperature rises, the Pressure increases…

The second factor: The Humidity factor is that all Powder contains molecular Water (not all is “dried out” during either Sulfuric Acid washing in Nitration, or by the Alcohol-Acetone method;) High temperature also drives out the water, and this causes the Nitrocellulose to become more sensitive and produce a Higher pressure (and temperature).

Thus “tropical” ammo is loaded especially for the High temperatures (lower Powder charge)…a fact noted by the Australian manufacturer during the First Gulf War, when Normal 7,62 and 5,56 made for Australian Climatic conditions performed badly in Iraq. A similar reverse problem occurs with ammo which is meant to be used in Arctic areas. (higher Powder charge for same results as in temperate ziones.)

Tropicalised ammo (German) was also better sealed, to prevent humidity being absorbed during the cold nights in the desert ( condensation in cold nights after extremely hot days…)

Regards,
Doc AV
AV Ballistics