7 Penna ctges


#1

The cases are heavy because they have thick walls.
They are turned on a lathe and have no hstp.
The inside of each case is in fact 5 mm shorter than the outside length
The cases have the name Penna engraced on the side.
Different calibers exist, most of them rimmless

From left to right
7 x 23 rimmless (7penna QS engraved on the side) with a standard bullet
7 x 28 rimmless (7penna QS engraved on the side)
7 x 33 rimmless (7penna QS engraved on the side)
7 x 28 rimmed (7penna QS engraved on the side)

The rimmless ctges are shot in a NON locked bolt gun.
Therefore the walls of the case must be thick enough to stay attached to the last 5mm of the case already out of the chamber when the bullet leaves the barrel.

The 7x23 is shot in a converted 1911 colt pistol with a fixed barred.

The concept of these ctges is to shoot very light bullets at very high speed in order to achieve good penetration.

The bullets can be very light (hollow monolithic brass) for use within 5 meters (15 feet) or light (monolithic brass) for use farther.

Some high armor piercing bullets exist (monolithic aluminium).

From left to right :
a fired 23 mm case (you can see the swelling of the case)
a standard brass bullet
a very light brass bullet (you can see the hole in the base)
an high armor piercing aluminium bullet

I will give you weight measurements, velocity and other info in the next post;

JP


#2

I would have thought aluminium be too soft for an AP projectile. It seems an odd choice of metal.


#3

Hi Falcon

No. if you want an AP bullet, many parameters are important.

  1. the VELOCITY of the bullet
    (take water for exemple, send it with a great pressure and you will cut any steel plate).
    Higher is the velocity easier is the penetration
  2. the HARDNESS of the bullet
    Harder is the bullet, easier is the penetration
  3. the diameter of the bullet
    Smaller it is easier is the penetration

So it is very easy,take a high velocity very hard small diameter bullet and you will drill anything !

BUT !!!

  1. To have an high velocity bullet it must be LIGHT (in a given caliber).
  2. And lighter is a bullet, quicker it looses its velocity !!
  3. Harder is the bullet, heavier it is (with regular materials)
  4. Smaller is the diameter, less lethal it is
  5. To have a knock out effet, you must have an heavy bullet (we do not talk here of bullets exploding at the impact)

So you have to choose a compromise.

It is what the people have tried to do:

  • using a steel (or tungstene or uranium or ceramic insert (which are harder than lead)
  • reaplacing lead (weight =11,34) by tungstene (weight =19,05) or uranium (weight = 19,25) , in order to have for the same weight a smaller diameter
  • making bullets with a pointed shape to decrease the impact diameter
  • increasing the velocity
    and so on
    (I am not talking of the pyrophoric aspect of uranium which is a must)

Now as I told you, lighter is the bullet , quicker it will loose its velocity.
So no need for example to make a rifle bullet very good at ten meters if the result is a disaster at 100 meters !!

It is for that you have two different regular bullets for Penna ctges.
One for less than 5 meters the other one for about 15 meters.
The specifications of the customers want that because they say people in the field can change magasines during a fight depending if the target is close or far !!
It is totally idiot I think but like all the PDWS ctges it it “in”.
What they want is to drill an hole in bullet proof jackets.
And as I told you lighter is the bullet less knock out you have.
It is good to pierce a bullet proof jacket at 20 meters for example but if you have no result on a guy having no bullet proof jacket a little bite farther it is a problem , isn’t it ?

I will give you in the next post the specifications of the Penna ctges and you will discover that at certain distances it is less powerfull than an air pistol pellet at close range !!!

JP


#4

J-P - Excellent summary!!!


#5

Thanks John !

To give some idea how difficult could be the compromise for an effective AP bullet, here is a small story.

Some years ago I used to make AP trials with 9 para ctges shot in my Beretta 92.

Bullets tested were :
common jacketed ones
German black bullet ctges from the war
German grey bullet ctges from the war
THV
Sieb
Arcane
KTW
and so on

The target was a steel plate (I do not remember the thickness) at about 10 meters away.

But the only thing I remember was :
KTW and THV had a false reputation !!,
Arcane was good but too much, a lot too much, pressure,
Sieb was very good.

And do you know the best one ??
The grey German bullet !!

JP


#6

Isn’t it incorrect to call the KTW an AP bullet as it was only designed to penetrate relatively light sheet metal and glass windows of car bodies, not any sort of armour plating. I’m sure there was a debate about this on this forum a while ago.


#7

Hi Falcon !
You are surely right.
I am talking about the reputation they had in France : good AP rounds.
JP