9mm largo


July 5, 2010, 12:54 AM
My brother was given a spanish surplus Destroyer rifle chambered for 9mm Largo. I would like to hear reloading tips and feedback from anyone who currently reloads for this caliber. I would really like some first-hand feedback from anyone who uses cut-down .223 cases, and even with all the searching I've done, I can't determine whether or not 38 super cases can be used. It seems as though .223 cases are not wide enough, so how will that work?

I have searched until my computer bled, and most of what I found was simply "don't shoot 38 super or 9x23 Win in 9mm Largo guns." I am looking for people who have some form of hands on experience reloading this cartridge. Tips and feedback.

Thanks guys.

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July 5, 2010, 01:24 AM
Starline usually has largo brass in stock for a pretty reasonable price. IMO forming from .223 isn't worth the effort.

As to loads I simply treated the largo as though it was a 9x19 with extra case capacity.

July 5, 2010, 02:11 AM
Do NOT use std. 9mm data! Loading data and more is available here:
For all things Largo go here: http://www.9mmlargo.com/index.htm

The .223 conversion comes up short on the rim diameter and you can have extraction issues. Also, because of the thicker case walls and reduced area in the rim area even after fire forming, the case volume is reduced from the standard so start 10% lower than you normally would when working up loads for that brass. Before Starline started selling Largo Brass, I bought their 9mm WinMag brass (9x29) and trimmed it back to 23mm in length. Whatever you do, do NOT try to shoot 9x23 Winchester ammo in it as you could lose body parts!

July 5, 2010, 05:21 AM
Why Spain elected the 9mm Largo, instead of just using .38 ACP, I will never understand, other than stubborn pride, and just to screw with things like the British liked to do in their way.


It is so close to .38 ACP, yet minutely different for rim diameter and other things.

I have heard that in practice, the two will usually interchange without issue...and, far as I can tell, their loadings/ballistics would be the same.

It is no slouch, with standard Pistol loadings usually being 125 Grain Copper Patch Bullet doing 1100-ish FPS.

Loading Density will be the same as .38 ACP.

But Loading Tables for .38 ACP are kind of fallen from fashion by now.

Some older Loading Handbooks seem to confuse .38 ACP with .38 Super, or, they neglect to make a clear distinction, so watch out for that.

9mm Loadings would not interchange, since the 9mm is a lot shorter Case.

July 5, 2010, 07:58 AM
9mm Loadings would not interchange, since the 9mm is a lot shorter Case.

I beg to differ

there are many examples of a cartridge like 38 special using the same charges as 9x19 for the same powder/bullet weight

for example with 125g bullets using WW231 as per hodgdon the max loads are as hollows

.38 special---4.9g
.38 Super----5.7g

using titegroup

.38 special---4.6g
.38 Super----5.0g

Based on this alone I'd be much more reluctant to use 38 super data than I would 9x19

July 5, 2010, 03:22 PM
Hi Krochus,

Oh, well...maybe so then!

Maybe with the Case size difference, and pressure difference, between 9mm Largo/.38 ACP, and, 9mmP'08, and .38 Special, for a Bullet of equal weight and seating depth, it ends up working out fairly close afterall, or falling on a proportioned scale.

But yeah, .38 Super, being transposed to 9mm Largo/.38 ACP, would be too much pressure.

9mm Largo might even chamber and be fire-able in some .38 Special Revolvers, for that matter.

I know .38 ACP does.

.38 Special, being a longer case, one would want to keep an eye on the proportions, as suggested in the comparison of Tables between .38 Special and 9mmP'08, when trying to imagine Loadings for 9mm Largo, who's pressure limit and case length is right about in the middle between them, or maybe a little above the middle actually pressure wise.

One would want to keep a clear head if trying to work things out that-a-way.

The Sub-Machine Guns or Carbines in 9mm Largo, may even have used a little hotter Ammunition for all I know, too.

July 5, 2010, 04:19 PM
Thanks for the feedback guys, I guess Starline is the way to go. Hope you had a happy 4th.

July 5, 2010, 08:53 PM
Still, when you have Proper brass and Proper loading data available, why risk using loads for a case that is 4mm shorter and has less volume?

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