9mm HP L7A1 "high pressure load" & testing

Do your L7A1 cartridges carry the NATO mark on the headstamp?

I don’t know if the question is addressed to me, but yes, my " + HP L7A1 91 " cartridges have the NATO mark on the headstamp. I have not seen any of these that did not have it. Why it has it is another question. My information is that this is not a NATO-normalized loading.

John Moss

Fox… (sorry, your nom-de-guerre is a little too complicated for me to memorize), yes, the headstamp is the same as described by John, including the NATO design mark.

Thanks John & JPeelen.

Bought a pile of this stuff back when it was coming through the gunshows, ran mostly in an Uzi carbine (A model), but some through G19 and G17 pistols with no ill effects noted, but caution is advised as per above recomms. Perceived recoil definitely above normal in handguns. Ran it in an armored-glass test for a local company around 2000; penetration slightly above other ‘hot’ FMJs (bullet profile more of a factor; 123gr Fiocchi FMJTC ‘Combat’ load surpassed it). It’s been an awfully long time, but I recall sending this, the blue-tip and black-tip IMI ‘CARB’ loads to DiFabio’s “AmmoLab”, where pressure testing on all 3 did indeed show to be high (do not recall test method or figures). If Heck freezes over and I find my chrony and other notebooks from back then I’ll post updated #'s. I’d heard that altitude as well as temp figured into the original ‘hot’ spec, but that’s gun-show hearsay.

Well, I did a little “tearing apart” and below are the results. Firstly, some remarks. I had wanted to test a cartridge of Hirtenberger manufacturer but a different load, so I tried to disassemble my only dupe of an L12A1 round, dated 92 (Lot 23-20-92 (pistol). However, after actually wrenching my hand a little pounding my inertia bullet puller on to a steel anvil about 15 times, and not even budging the bullet, I gave up on that. For comparison, the L7A1 bullet came out on the 3rd “whack.” So, I choose to take apart a Winchester military round, Lot WCC90-007 instead, and the bullet came out on the 2nd or 3rd hit.
My hand still hurts from the stubborn one.

Secondly, this is NOT a scientific test. The powders in the two cartridges are different - both very fine grain but black for the Hirtenberg and a greenish color for the Winchester. I cannot identify the name or number of the powder.

So, the following is presneted only for what little interest, and less importance, might be there for the followers of this thread:

Cartridge: Hirtenberger manufacture, lot number HP 20/91, headstamp + HP L7A1 92.
Cartridge case material: Brass
Primer type: Boxer, brass cup, red primer seal
Overall cartridge weight: 12.46 grams (192.4 grains)
Powder charge weight: 0.47 grams (7.2 grains)
Bullet type: GMCS RN FMJ
Bullet weight: 8.02 grams (123.7 grains)
Cartridge lot number: HP 20/91

Cartridge: OLIN Corporation, 9mm Ball NATO M882, lot number WCC90-007, headstamp + WCC 90
Cartridge case material: Brass
Primer type: Boxer, brass cup, red primer seal
Overall cartridge weight: 12.60 grams (194.60 grains)
Powder charge weight: 0.39 grams (6.0 grains)
Bullet type: GM FMJ RN
Bullet weight: 8.07 grams (124.5 grains)
Cartridge lot number: WCC90-007

While again I admit that it proves really nothing, you can see that the powder charge of the Hirtenberger L7A1 round is substantially larger than that of the Winchester (Olin) 9 mm NATO M882 round.

I wish I could have successfully done the second study with the Hirtenberger L12A1 round, but I wasn’t sure which would break first, my bullet puller or my hand. I have never had any experience with pulling bullets from self-loading pistol cartridges being a complete failure. Some over the years have been more difficult than others, but the end result was always the same, a successfully removed projectile. Sorry for that.

John Moss

John, put the complete cartridge between two pieces of plywood or cardboard into a vice and slowly push the bullet inside the case, just a very tiny bit, this wil break the glue or stuf that prevent the bullet pushed out in te puller. (My expirience with Dutch 9x19 AE and NP cartridges) Secondary, (but destroiing the case and good measurment of the weight a little) saw the casemouth half diagonally a little so the bullet can move.
Good luck, Jaco

Jaco - thank you, but I am aware of that technique, which was a good suggestion from you since it almost always works. However, I have a very small plastic-jaw, swivel-head vise which is not very strong. I tried doing just that, and quit since I could not budge the bullet (push it into the case) any more than I could pull it out with an inertia bullet puller. I did not want to damage my vise. Never seen anything like it. Had I had a duplicate of the L12A1 round, I would have worked the bullet out by distending the case mouth, but I actually was already breaking my own rule of never disassembling the only specimen of a cartridge from my collection.

I would have much preferred the comparison to have been between the L7A1 and the L12A1, since both of my cartridges were made in the same year and likely would have had the same powder and powder-charge.

John Moss

Johnn, I totally understand your frustration, I’ve had this a few times too, but I have a big heavy vise haha. And I have the same rule, I never unload an one only specimen in my collection…

JPeelen - Have you had the opportunity to conduct any pressure tests on the Hirtenberger L7A1 cartridges at this point? Thanks.

I’ve tested the L7A1 in a CZ with a 4.5" barrel, as well as an EVO with a 7.72" barrel, as well as a Glock 19 from time to time testing armor. At 124gr it’s peaked at about 1,272 in the Glock 19. Looking back at various rounds I have not fired any 124gr at speeds greater than that…

Your question is very legitimate.
No, I am currently waiting for a response from the Cologne proof house to my Email of March 16th.
Cologne had been recommended to me. Easter Holiday may have played a part.

Before that I had already lost two weeks contacting the Kiel proof house (which is closest to where I live) before getting a negative response. In earlier years DEVA (a private organization) had done all my pressure measurements. But events have led me to lose my confidence in their current work.

JPeelen - Thanks. I look forward to your results when/if you are able to complete the testing.

Yesterday I received from the Munich Proof House the gas pressure results for the British 9 mm x 19 L7A1 cartridge as manufactured by Hirtenberger (Lot 10/91).

The L7A1 yields 114 percent of the maximum CIP pressure.

The average from 20 shots was 2687.9 bar compared to 2350 bar CIP limit. That is 14 percent too much for safe shooting, but not as much as one would expect after a sinister warning about ammunition made “specially for use in submachine guns under adverse conditions”.

As a rule of thumb, commercial ammunition is loaded to about 90 percent of the CIP limit. That means, the L7A1 is about 24 percent “hotter” than a typical 9 mm Luger from a European shelf. It is about 6 percent hotter than the Bundeswehr DM11A1B2, which, according to Bundeswehr figures, yields 2548 bar when measured in a CIP barrel. The DM11A1B2 was fired from 9 mm handguns by military and police over decades, before it was replaced by still hotter loads.

How does it compare to the older UK 9 mm Mark IIz? I had sent in also 20 rounds from Hirwaun production of 1944 (date stamp on the label unreadable). Measured pressure of these was 89 percent of the CIP limit. This is in line with Mark 2z of Radway Green manufacture from 1958, which another institution measured for me in 2013 (15 rounds). Pressure was slightly higher, but at 94 percent of the CIP limit still safe. Both had nearly the same muzzle velocity from the 150 mm (6") CIP barrels: 405 and 407 m/s (about 1330 ft/s). The bullets are lighter at 7.5 g, compared to the 8 g of the L7A1.

The Hirwaun Mk IIz cartridges have really hard primers. A pistol firing pin leaves only a rather small impression. About 12 out of 15 cartridges needed a second blow in my P9S to fire. I believe the “for submachine gun” image of the Mark IIz may come from the hard primers. The Radway Green Mk 2z lot had only 1 in 15 that required a second blow.

To conclude I would like to thank Ralf Abel very much. His generous donation of L7A1 cartridges laid the base for finally being able to arrive at hard facts regarding L7A1 pressure.

4 Likes

Good Morning From S.E. Virginia (USA) Mr. Peelen,
Thank you so much for this information. It has answered a long-standing question for myself and several of my fellow firearm enthusiasts. One question though. In your own personal opinion, and if you have any data on this, does a 24% increase in the CIP of off the shelf standard European 9X19m/m close to, or possibly exceeds, the CIP of off the shelf American +P+ 9X19m/m ammunition. Again, many thanks.

Best Regards,
James Manley
Proprietor - Foxfire Rod & Gun

Foxfire Rod & Gun

A gun may save your life…ONLY JESUS can save your soul! John 14:6

JPeelen
June 11

Yesterday I received from the Munich Proof House the gas pressure results for the British 9 mm x 19 L7A1 cartridge as manufactured by Hirtenberger (Lot 10/91).

The L7A1 yields 114 percent of the maximum CIP pressure.

The average from 20 shots was 2687.9 bar compared to 2350 bar CIP limit. That is 14 percent too much for safe shooting, but not as much as one would expect after a sinister warning about ammunition made “specially for use in submachine guns under adverse conditions”.

As a rule of thumb, commercial ammunition is loaded to about 90 percent of the CIP limit. That means, the L7A1 is about 24 percent “hotter” than a typical 9 mm Luger from a European shelf. It is about 6 percent hotter than the Bundeswehr DM11A1B2, which, according to Bundeswehr figures, yields 2548 bar when measured in a CIP barrel. The DM11A1B2 was fired from 9 mm handguns by military and police over decades, before it was replaced by still hotter loads.

How does it compare to the older UK 9 mm Mark IIz? I had sent in also 20 rounds from Hirwaun production of 1944 (date stamp on the label unreadable). Measured pressure of these was 89 percent of the CIP limit. This is in line with Mark 2z of Radway Green manufacture from 1958, which another institution measured for me in 2013 (15 rounds). Pressure was slightly higher, but at 94 percent of the CIP limit still safe. Both had nearly the same muzzle velocity from the 150 mm (6") CIP barrels: 405 and 407 m/s (about 1330 ft/s). The bullets are lighter at 7.5 g, compared to the 8 g of the L7A1.

The Hirwaun Mk IIz cartridges have really hard primers. A pistol firing pin leaves only a rather small impression. About 12 out of 15 cartridges needed a second blow in my P9S to fire. I believe the “for submachine gun” image of the Mark IIz may come from the hard primers. The Radway Green Mk 2z lot had only 1 in 15 that required a second blow.

To conclude I would like to thank Ralf Abel very much. His generous donation of L7A1 cartridges laid the base for finally being able to arrive at hard facts regarding L7A1 pressure.

1 Like

hello
if i’m not wrong these L7A1 had same pressure than swiss 9mm PP41 service ammo

Sorry to rain on your parade, but I had also 20 rounds of Swiss Pistolenpatrone 41 in my package to Munich. Made at Thun on 30.03.81.
Although their average pressure was 97 percent of the CIP limit, they were manufactured so consistently that not a single shot of the 20 exceeded the allowable variation.
Muzzle velocity of the 7.99 g bullets (average of three disassemled cartridges in the box of 24) was 373.1 m/s from the 150 mm CIP barrel versus 423.9 m/s of the L7A1.

The problem is in the different methods of SAAMI and CIP. The figures are not really comparable.

9 mm +P is offered here in Germany (by Frankonia, fo example). That means it must have passed the CIP ammunition qualification. In other words, the pressure is not higher than CIP limits.

9 mm +P+ ammunition (also not defined by SAAMI, if I am correct) I have never seen and also did not encounter any documented CIP measurements. I wish I could get hold of a box at a collector’s meeting over here.

Jochem, very interesting, thanks for sharing.

According to HP literature from the 90’s, the pressure of any of their 9 mm cartridges is ≤2600 and also their recommended maximum pressure for reloading (maximum permissible pressure according to Önorm S 1380).

Regards,

Fede

Yes Fede, that is the old figure used with the copper crusher method. You find it also in German proof decrees of 1976 and 1991. In January 2000, the 2350 bar is listed.

In ammunition books of the 1930s you will find even lower numbers: 2200 by RWS and 2300 by DWM.