9mm Largo brass....got lucky (?)

[Der Gebirgsjager]

It had been awhile since I checked Starline's website for 9mm Largo brass. Whoa..there is was, in stock, your choice in amounts of 500 or 1,000. I went with 1,000 for $194.00 ground shipping paid. If you load and/or shoot the Largo cartridge take heed, because they very often don't have it in stock, and the price isn't going to go down.

DG

[atfsux]

I lucked out last year when they had a batch of 9x23Win, which is dimensionally the same, but different headstamp. Both can be used for loading either cartridge,...BUT,...it is NEVER a good idea to load Largo brass to 9x23Win pressures, simply because while you may know not to shoot it in a weak Largo pistol,...if someone else comes upon your ammo and does NOT know,...KABOOM!!!!

So I take care and expense to only acquire the 9x23Win headstamped brass, just to avoid that kind of accident.

[Der Gebirgsjager]

An astute observation, atfsux. Not a problem with me, as I don't own any 9x23s. Mine are all Llamas, Stars, and Astras. Many are stamped "9mm/.38" and it's sometimes a problem to convince the uninitiated that the ".38" was .38 ACP and not .38 Super. Not long ago I added a Llama 9mm/.38 to my collection that had been fired with .38 Super and had a broken barrel link. No doubt 9x23 would have been much worse.

DG

[lar45]

I have a Star Modelo Super in 9mm Largo. I cut avrecess for a semi rim in the barrels hood and now it shoots 38 super.
Thanks for the heads up on the brass, I should order some.

[dtknowles]

I lucked out last year when they had a batch of 9x23Win, which is dimensionally the same, but different headstamp. Both can be used for loading either cartridge,......

You know this how? I was told to be careful when using 9mm Largo data with 9x23 Win brass as the 9x23 Win has thicker webs and lesser capacity. Also vise a versa, don't use 9mm Largo brass with 9x23 Win data as the cases are not up to the higher pressures.

That said I have not sectioned these cases or measured their capacity or the capacity of my 38 super brass that has the rim turned down to function in my CZ-52 I rebarrelled to my sort of wildcat 9x23 long. By long I me longer COAL. Before I could find 9mm Largo or 9x23 Win brass I was using the modified 38 super brass as it is easy to turn down the rim and that is a must because they won't go into the magazine if they are not trimmed. The magazine will take ammo with a longer COAL so I take advantage of that with my cast bullet handloads (with everything but light bullets) to have more case capacity for powder. More case volume means higher velocity with lower pressures. Or said the other way around smaller case capacity means higher pressures for the same velocity.

There are actually a number of similar but different 9 x 23 cartridges; 9mm Largo, 9mm Steyr, 9mm Bergmann-Bayard, 38 ACP, 38 Super, 9 x 23 Win.

It could be that Starline 9mm Largo and 9 x 23 Win cases are identical except for the headstamp. I was just asking how you know this?

Tim

[atfsux]

You know this how? I was told to be careful when using 9mm Largo data with 9x23 Win brass as the 9x23 Win has thicker webs and lesser capacity. Also vise a versa, don't use 9mm Largo brass with 9x23 Win data as the cases are not up to the higher pressures.

That said I have not sectioned these cases or measured their capacity or the capacity of my 38 super brass that has the rim turned down to function in my CZ-52 I rebarrelled to my sort of wildcat 9x23 long. By long I me longer COAL. Before I could find 9mm Largo or 9x23 Win brass I was using the modified 38 super brass as it is easy to turn down the rim and that is a must because they won't go into the magazine if they are not trimmed. The magazine will take ammo with a longer COAL so I take advantage of that with my cast bullet handloads (with everything but light bullets) to have more case capacity for powder. More case volume means higher velocity with lower pressures. Or said the other way around smaller case capacity means higher pressures for the same velocity.

There are actually a number of similar but different 9 x 23 cartridges; 9mm Largo, 9mm Steyr, 9mm Bergmann-Bayard, 38 ACP, 38 Super, 9 x 23 Win.

It could be that Starline 9mm Largo and 9 x 23 Win cases are identical except for the headstamp. I was just asking how you know this?

Tim

I am trusting others who have investigated this and reported elsewhere on other forums. But in my own experience, although I haven't sectioned the different headstamps myself either, I have in fact on a few occasions when 9x23Win headstamped brass was simply unobtanium back many moons ago, used some Largo headstamped brass for 9x23Win ammo I loaded up. Later, when the proper headstamps were available, I acquired and used those. Both were Starline products. Loading was identical on my part. Chronograph data showed zero differential in practical results. Inspected brass showed no differing signs of pressure between the two. Functioning was 100% reliable with both. No detectable difference in extractor groove or rim dimensions.

[Sandspider500]

I think my starline 9mm largo fired cases measured 16.8gr of water. A

[Sandspider500]

Starling 9x23 comp brass measures 17.4gr of water.

[dtknowles]

Thanks Spider. Did you do the measuring to fired brass? Were they fired in the same chamber. Not criticizing just getting clarity. I am thinking about maybe measuring some of the brass I have on hand. What is your technique? Do you set the case on the scale and then add water until it is full? 17.4/16.8=1.036 or about a 3.5% difference in capacity seems like it would not matter seems really small. Consider that the bullet takes up about half that space, so it is really more like a 7% difference in the combustion chamber volume. So, we see a small but not insignificant difference in volume. If all that difference was in the web of the case head it would add a ring .15" tall and .009" thick to the head of the case making the case quite a bit stronger. I think what I was told "to be careful when using 9mm Largo data with 9x23 Win brass as the 9x23 Win has thicker webs and lesser capacity. Also vise a versa, don't use 9mm Largo brass with 9x23 Win data as the cases are not up to the higher pressures" is good advice. I am going to measure some of the cases I have and post the results here.

Tim

[Sandspider500]

I zeroed the scale with the fired largo case then added water with a eye dropper till it was full. The 9x23 water capacity was taken from an American rifleman article and were measured by the author. He measured Remington 38 super +p at 17.7gr, Winchester 38 super +p at 17.1gr, a starline 9x23mm comp at 17.4, a cut .223 Remington case to .897 at 14.4gr, a fiocchi 9mm at 13.8gr and a 9x23 Winchester brass case at 15.7gr.

[Sandspider500]

I also did some 9mm fired brass too if your interested.

[dtknowles]

Ok, I did my measurements. Data below.

Confirmed 9 x 23 win is the beefiest with the smallest capacity

9 x 23 Largo is lighter with more capacity

7.62 x 25 brass is pretty beefy too.

38 super is the lightest and has the most capacity.

Maybe now we know why people were blowing up guns hot rodding 38 super.

My water numbers might be a bit different that others, I noticed that you have to be careful to maintain a consistent meniscus. The water would really dome up if you let it. I used the smallest meniscus that would still fill the case full to the brim.

Virgin Starline 9mm Largo brass with spent primer

67.9 gr empty
85.0 gr full of water
17.1 gr water capacity

Win 38 super auto + p with the rim turned down fired

65.7 gr empty
83.8 gr full of water
18.1 gr water capacity

FC 38 super + p with the rim turned down fired

68.4 gr empty
85.0 gr full of water
17.6 gr water capacity

S&B 7.62x25 expanded and shortened to 23mm fired

70.2 gr empty
87.0 gr full of water
16.8 gr water capacity

NNY 1953 headstamped 7.62x25 expanded and shortened to 23mm fired

71.5 gr empty
88.3 gr full of water
16.8 gr water capacity

Win 9x23 Win unfired factory loaded round, pull bullet and dumped powder

69.6 gr empty
96.1 gr full of water
16.5 gr water capacity

Tim

[dtknowles]

I also did some 9mm fired brass too if your interested.

Sure, if you took measurements you should share the info and the world will be better for it.

Tim

[dtknowles]

For most of the loading that most of us do, the brass is probably interchangeable but if someone is loading max loads or trying to push some limits it is best to know all the variables.

For more than a century people have been trying to turn 9 x 23 and 38 super +p into ,357 Magnums all the while the factories have been toning down .357 magnums.

I have loading manual pressure data that says 9 x 23 win runs at higher pressures than .357 mag and 38 super +p runs at lower pressures. I expect that 9mm Largo runs even lower pressures. I measured the head diameter of some ammo and 38 super ran 0.005" smaller than 9 mm Largo and 9 x 23 win. I think it is understood that you should not shoot .38 super in guns meant for 9 mm Largo but it bares repeating.

Tim

[Sandspider500]

9mm
WCC 13.2gr
RP 13.3gr
TRN21 13.3gr
Aguila 13.3gr
GFL 14gr
Ammo inc 14.1gr
WNA 13.3gr
MXT 13.8gr
S&B 13.5gr
FC 14.1gr

A correction on my earlier 9mm largo measurement, it was a sized case and it measured 16.6gr water.
Before CCI decided to produce 9mm largo ammo, they did some investigating. They acquired some European surplus and commercial lots of 9mm largo and tested them in piezo-electric pressure barrels. They grouped in two distinct pressure levels, a bit under 30,000 psi and 36,000 psi. They also had acquired a bunch of pistols for function testing and had them checked by ultra violet inspection. They found that the Astra 400 slides had small cracks in them. Most of the star pistols showed only typical wear from the slide hitting the frame. They decided to make the MAP 30,000 psi, and said most velocity goals were met under that pressure.


Description: 9mm largo 6gr longshot
Notes 1: lee 356 125 2r
Notes 2: oal 1.260
Distance to Chrono (FT): 10.00
Ballistic Coefficient: 1.000
Bullet Weight (gr): 128.000
Altitude (FT): 0.0
Temp: N/A
BP: N/A
Shots
# FPS FT-LBS PF
8 1204 412.08 154.11
7 1141 370.08 146.05
6 1177 393.80 150.66
5 1157 380.53 148.10
4 1167 387.14 149.38
3 1184 398.50 151.55
2 1140 369.43 145.92
1 1174 391.80 150.27
Average: 1168.00
StdDev: 21.73
Min: 1140
Max: 1204
Spread: 64
True MV: 1169.33
Shots/sec: 0.18

[Rockindaddy]

Lots of great information here! Have an Astra Model F with original shoulder stock. I am running out of original 9mm Largo ammo. Some of the primers are bad too. Not fun when the gun stops running about half way through a 20 round magazine. Thought maybe 38 Colt Automatic or handloaded 38 Super with a cast boolit might work. My Colt 1902's work well with 38 Super handloads. Will try em in the "F" model. The Colt 1902's are tender and will not handle a heavy load. The Astra takes a stiff charge to operate the action.

[dtknowles]

320553

On the left and the right are my handloads and the center left is a vintage 38 acp with the headstamp WRA Co. 38 AC the center right is some sort of 9 x 23 mil surp with no headstamp. Notice the difference in COAL, makes a real difference in capacity. I think maybe some pistols in 9 x 23 have longer magazines than M1911's that mil surp exceeds 38 super max COAL

Tim

[Der Gebirgsjager]

It arrived!

DG

320632

[Sandspider500]

Well, let's see em.
320707

Left to right
36-170N, MP 360-640, MP 356 130 2r, Lee 356 125 2r, Lee 256 124tc, Barnes 115 tac-xp

[Battis]

I have an Astra 400 in 9mm Largo that also shoots 38 ACP. I have a Colt 1903 Hammer in 38 ACP that does not shoot 9mm Largo.
I use 38 super brass for the 38 ACP but never the 38 Super loads.

The Astra 400 came with approx 200 vintage rounds. One out of that 200 actually fired - all the Berdan primers were bad. I pulled the bullets for reloading.