7.9 German primer problem


#1

This is the messiest German factory primer which I have ever seen. It came from a full box with this being the only one like this. Primer hole too small or too dry ?


#2

War production.

Dutch


#3

NICE


#4

Dutch, What is the headstamp on your double extractor groove cartridge? I have never seen anything like that before. I take it it is a 7.92x57.


#5

Hi Falcon

Here is the head stamp


#6

Same as CSA’s one with the damaged primer, a late-war date. Still, when yours got out of the factory, was the quality control officer on the production line just not looking?


#7

Good quistion, perhaps some nice girls walking around. -:)


#8

Much if not MOST of German war production of ammunition was done by slave labor. Slave labor quality control CAN be a real problem. Given the condition of the population.

I started off to research this some years ago with an eye toward comparing slave labor production and non-slave labor production. The catalogue of companies which used slave labor is so huge that it is a waste of time to try to figure it out. Many companies which did not use slave labor in their main factory used it in subsidiary factories which fed into the main.

1944 was a year of flat out go for broke production. To get 2 extration grooves the shell had to go through twice. I suspect that the support for the shell malfunctioned and it went through the machining step twice instead of being kicked out the first time.

The fact that it was grooved so high up and that it is symmetrical indicates that it went through the second time too low. I suspect that a positioning cam failed on the first cut and it went through again lower the second time. It was kicked out the second time and proceeded with the following automatic processes. Some machines are doing the same process to several rounds at the same time and anything in the production space gets worked. It could have started out in space 1 and was still in production when it hit space 2 due to a cam failure. Machines will perfrom lots of tasks if there is a shell there or not depending upon the design format.

Why do cams fail? Many reasons usually dealing with lubrication , wear or metal fatigue issues. Obstruction is also an issue. Some obstruction can cause a machine failure which is not repeated. A mouse , leaf , lump of dried lube can cause a cam to stick and make a repeating or NONrepeating error in manufacture.

Inspectors?

I think one of the reasons that Germany used such specific marking and labeling was that much was left to automatic inspection after tooling up. Much of this is based upon weight and size and there are production parameters involved with all of this. If there was failure at the PROOF stage the shell could be traced back to ALL component manufacturers.

Consider the millons of rounds of 7.9 made and the FEW such errors seen and you get an idea of how good the autoinspection was.

I have seen ten of thousands of rounds of 7.9 and this odd primer is the only primer screw up of this nature which I have seen. I have NEVER seen one like what DUTCH put up.

The primer stakes imply that this could have been a loaded round but hard to tell from the photo. I doubt that this double groove would keep the shell from working which is,of couse, the acid test of any ammunition. There may have been many of them which fired just fine.


#9

I appreciate that there were so many factories making ammunition in Germany that there were bound to be a few errors. As for quality control being a problem with slave labour, Polish slave labourers who worked on making the guidance gyros for the V-1 flying bombs are known to have urinated on them. They knew this would cause the delicate mechanism to sieze within a few days due to corrosion, and the bomb to spiral out of control shortly after launching. I remember hearing this on a British documentary about WW2, and seem to remember they had some footage of a V-1 losing control after launching due to this.

I also found out from this documentary that the British also defeated the German type “25” air dropped bomb fure due to poor quality control. This was armed when the windmill on the bomb’s tail stopped spinning after landing, so a bomb that otherwise failed to detonate could not be moved without detonating. It worked with two glass cylinders filled with mercury with a contact at each end. When the mercury completed this circuit if the bomb was moved, it would detonate.

British EOD personnel were being killed in accidental explosions, and no-one knew why, until one very lucky EOD technician removed one of these fuses by hand from a bomb that had already been moved a few hunderd yards. The only reason it did not detonate was that a single joint in the circuit had not been correctly soldered, meaning that the detonator circuit was not completed when the bomb was moved.

Now they knew how this fuse worked and it had “25” stamped into it (which had not been seen before), it could be disabled by moulding a clay cup over the fuse head on the outside of the bomb and filling this with Liquid nitrogen. The Liquid nitrogen would cause the batteries to fail due to the extremely cold temperature. Apparently after the Germans learned that Britain had learned how to disable these fuses, they were never used again, and the General in charge of the department that designed them was furious that how to disable them would probably never have been learned if quality control procedures were followed. It did not ever say whether these were made in factories that used slave labour.


#10

CSAEOD

The second extractor groove is well forward on the case and must surely seriously weaken the case at the vulnerable junction between the case wall and the solid head. I would think that a rupture here was very likely.

gravelbelly


#11

I would like to know more about this case. The photo does not clearly show primer details.


#12

Totally fascinating history and logic. Really enjoyed reading this. The double extractor groove shell reminds me of the famous upside airplane stamp printing error. It really is pretty remarkable that their are not more manufacturing defects considering the incredible numbers of units a factory makes. It is also amazing how much you guys know. blown away :-)


#13

CSAEOD

The second extractor groove is well forward on the case and must surely seriously weaken the case at the vulnerable junction between the case wall and the solid head. I would think that a rupture here was very likely.

gravelbelly[/quote]

You could be right. I would like some more details about this case if possible. The primer can not be seen well enough in this photo.


#14

CSAEOD

The second extractor groove is well forward on the case and must surely seriously weaken the case at the vulnerable junction between the case wall and the solid head. I would think that a rupture here was very likely.

gravelbelly[/quote]

Are you suprised that the top groove did not cut through the wall ?


#15

[/quote]

You could be right. I would like some more details about this case if possible. The primer can not be seen well enough in this photo.[/quote]

@CSAEOD

For you

Rgds,
Dutch


#16

THANK YOU. IS THIS LOADED ?


#17

Yes, it’s loaded


#18

Yes, it’s loaded[/quote]

amazing !


#19

Think the base will ripped of by firing this round.


#20

[quote=“Dutch”]@CSAEOD

For youRgds,
Dutch[/quote]

From the side it look great. from the bottom not so good. What annulus color do you make out ?
.