7.92x33 Pressure Test


#1

Does anyone have this loaded?


#2

No,

The only one I have ever seen was in 7,92x57 Mauser.
I think the 7,93 x 33 must have look the same.
(Pictures courtesy Woodin Lab)


Rgds
Dutch


#3

Not loaded but I came across that one somewhen:


#4

edited since posting became superfluous…


#5

Thanks Dutch.

EOD your case appears to have a very interesting squared rim. Can you post a HS?


#6

Will do soon, hopefully this weekend.
The hs did not look special (well I am not the measure in all this).


#7

May someone also enlighten me as to the purpose of all these cuts? I always thought that pressure test ammo was just ammo loaded with extra powder to create higher pressure.


#8

Boy, am I treading on thin ice trying to anser this. As every knows, my strong suit is history - I am not
too tehnically inclined. Well, here goes nothing. Vlad, those cartridges measure pressure by the “copper-
crush” method, in a special pressure-test gun. The round hole in the case, often covered just for
the purpose of handling without letting all the powder fall out, aligns with a small copper cylinder.
When the cartridge is fired, the gas escaping there causes the copper cylinder, held in a housing in the
pressure gun, to be crushed to a greater or lesser degree. Measuring the amount it is crushed tells
the pressure to those who know how to use this equipment.

The slot filed into the head of the cartridge is just so the cartridge, single-loaded into the pressure gun,
can end up with that round hole perfectly aligned with the copper-pellet. I do not know what there
is a huge difference in the size of holes in the sides of the cases of various CUP cartridges from different
makers and in different calibers.

If I have made any huge blunders in this over-simplified explanation, feel free to call me out on it.


#9

Vlad

There are several “High Pressure” cartridges. The most common are rounds used to proof-test completed firearms. And, there are rounds used to test unfinished barrels (autofrettage).

The ones shown here are used to fire in a special pressure gun to determine the pressure of standard cartridges. The taped hole is lined up with a piston that, in turn, has a copper cylinder on top of it that is crushed when the cartridge is fired. Measuring the copper cylinder before and after firing gives you the copper units of pressure, or CUP. The notch is used to align the cartridge in the pressure gun chamber.

There is also a locking-shot cartridge that is used to lock the piston hole bushing in place before firing the cartridge in the pressure gun.

That’s it in a nutshell. Now the guys who live for this kind of stuff can give you more details. ;)

Ray

P.S. John beat me to it. I’m a two finger typist and go slow. John’s explanation is better than mine anyway.


#10

Dvollmer, is this the same case illustrated in Senich’s book? It also looks like the one auctioned by Buttweiler.


#11

To my eyes this one is a fake. German ammo factories never produced pressure test rounds in such a poor quality. Have a close look to the shape of that hole. It is cornered and the rim seems to be worked with a file.

Rolf


#12

Fede, I purchased this from Buttweiller’s auction several years ago.


#13

Ray - Mine is not necessarily better. You covered a couple of points I forgot, such as the piston.
I think between the two of us, we probably did fairly well in making a simple explanation of the
process. Thanks for filling in my gaps.


#14

[quote=“RolfFoerster”]To my eyes this one is a fake. German ammo factories never produced pressure test rounds in such a poor quality. Have a close look to the shape of that hole. It is cornered and the rim seems to be worked with a file.

Rolf[/quote]

Hi Rolf,

Honestly, I have thought the same thing. Have you seen any other fake pt rounds?


#15

No, not in 8x33. The problem is that a very good fake is hard to identify and I always like to say that every collector has a fake in his collection.
I think this round should go to the fake collection of Bill Woodin.
Rolf


#16

[quote=“dvollmer”]Thanks Dutch.

EOD your case appears to have a very interesting squared rim. Can you post a HS?[/quote]

Ok, I added the hs above.


#17

[quote=“EOD”][quote=“dvollmer”]Thanks Dutch.

EOD your case appears to have a very interesting squared rim. Can you post a HS?[/quote]

Ok, I added the hs above.[/quote]

@ EOD, You were too fast.

Took a wile to find the case with your head stamp.


Rgds
Dutch


#18

Sorry :)


#19

This is the case in the collection of Bill Woodin that was illustrated in Senich’s book. The hole has the same shape as yours but I’m not sure what this really means. Same case? Same fake? Same faker?

I have a copy of a Polte drawing showing specifcations for this “Gasdruckhülse” and there are some evident discrepancies but I’m not sure if this is a conclusive indicative that you have a fake. As Rolf says, maybe the aspect of your case is enough to doubt it.


#20

The brass cases shown by dutch and me have the holes milled, not drilled. Just to point out that these were some sort of precision product. That of course does not mean that the shown 7.92x33 would not have worked as good as a milled one.