Cartridge Development the Hard Way: CCI-Speer 9mm Largo

When a major company develops a cartridge and submits it to the industry through SAAMI, other member companies enjoy a set of fully fledged specs, drawings, and test standards. It is more difficult to duplicate an old existing cartridge, such as a foreign one with no U.S. standards. CCI-Speer previously took up the challenge with the 9mm Makarov when large numbers of surplus Soviet Bloc pistols were imported in the 1990s without suitable ammo. Later the company took on another cartridge that was seldom if ever seen in the United States: the 9x23mm Largo.

About 1912, Spain adopted the German-developed 9mm Bergmann-Bayard cartridge, calling it the “9mm Largo,” meaning “large” or “long.” The cartridge was used extensively in pistols, sub-machine guns, and even a bolt-action carbine.

In the mid-1990s, thousands of surplus 9mm Largo pistols hit our shores. The smattering of Largo pistols previously in the U.S. were all being fed the wrong ammo, including 9mm Luger, .38 Super, and even .380 ACP. Obviously, the results were poor, even dangerous. The market needed proper ammo.

CCI found the Largo different from the Makarov project. The Russian cartridge had European standards, and “Mak” pistols offered few variables, with their basic ballistic parts built from the same drawings regardless of the factory.

Conversely, the 9mm Largo had few European guidelines, and imported pistols represented two very different semiauto designs. The Astra 400 was a robust but simple blowback action; the Star “A” and Star “Super” were near-clones of the Colt Government Model with John Browning’s proven mating of barrel to slide. Any new Largo ammo had to function properly in both action types.

Through channels, we were able to obtain small samples of European Largo commercial and surplus ammo. We tested those extensively in piezo-electric pressure barrels that we built using the tried-and-true SAAMI transducer arrangement. The sample ammo’s pressures clustered in two groups, most a bit under the 30,000 psi mark but showing a smaller population at about 36,000 psi. We worried the latter level was a bit stout for the blowback Astra 400. So we had to ask: To which pressure should we load? The pistols made that decision for us.

We acquired dozens of function-test pistols from distributors. We had no data on their history or provenance to help us judge condition or number of rounds fired. Prototype ammo would be heavily function-tested in production pistols, and some tests required hand-firing. Prudently, we had our R&D lab do thorough mechanical evaluations. We needed to know that the pistols were safe.

Ultra-violet inspection showed slides of a few heavily used Astra 400 pistols had tiny, short cracks extending upwards for some of the cut-outs in their rails, like for the slide stop. Although the cracks seemed to have stopped “growing,” this indicated a lot of use and caused our tech staff to recheck the Star pistols for stress. Most Stars only showed normal “slide-hits-frame” wear in patterns consistent with the recoil of many rounds, not parts breakage. Maybe we found where that 36,000-psi ammo went!

Based on detailed sampling, pressure tests, and firearms condition, we set the maximum average pressure at 30,000 psi, 5,000 psi under the 9mm Luger. Most production lots would make velocity goals at pressures lower than that.

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CCI’s resulting Largo offering was in the Blazer line, first with 0.355-inch Speer 124-grain TMJ bullets to match the bullet weight used in the majority of foreign ammo. A 124-grain HP loading was offered later. The nose profile of factory Largo ammo was quite close to the “NATO” nose profile of Speer’s TMJ, so feeding reliability was excellent.

The lower pressure assignment did not cripple the Largo. Fired from surplus pistols with barrels of 5.0 to 5.5 inches, Largo performance is nearly indistinguishable from U.S. 9mm Luger 124-grain ammo out of 4.0-inch barrels.

CCI eventually dropped the Largo after demand fell off, but today’s handloaders can create excellent ammo with reloadable brass cases from Starline. We used those for reloading data development, and they were very good. If a propellant worked well in the 9mm Luger, it was good in the Largo. Lab-tested data is available on the Speer website as well as in the #13, #14, and #15 Speer reloading manuals.

We published Largo reloading data for both 115-grain and 124-grain bullets. Although the specific pistols we used to test handload velocities were reliable with the lighter bullets, not all may be so forgiving. We showed loads for Gold Dot HP bullets as well, but successful feeding of HP bullets can depend on the individual pistol. Always test for feeding compatibility before you load up hundreds of rounds.

Issues with improper ammo and the confusing array of 9mm handgun cartridges over the last 120+ years led us to place gun-specific comments for that cartridge in Speer manuals that had Largo data. Some useful ones are reproduced here.

Most Spanish pistols marked “9mm/38” are chambered for the Largo. Similar models chambered for 9mm Luger are commonly marked “9mm/P08” or “9mm/08.”

Do not shoot 9mm Luger or .38 Super Auto in a 9mm Largo pistol. In addition to pressure issues, improper headspace can cause serious issues, including gas escape and shredded case heads.

There is a modern 9x23mm Winchester cartridge in production that has a maximum average pressure of 55,000 psi! Do not fire it in 9x23mm Largo pistols.

Some older, exposed-hammer pistols cloned from the Colt Government Model lack John Browning’s inertial firing pin. Lacking a proper inertial firing pin, safe hammer-down carry/storage must be with an empty chamber. If you have the slightest doubt about how to inspect for this type of firing pin, be sure to have a professional familiar with this handgun type do so.

With the right ammunition, the 9mm Largo pistols proved reliable. The Largo cartridge never overcame competition from the 9mm Luger and others, but Largo pistols from that influx in the 1990s gave their new owners affordable reliability in a handgun you could keep handy in places you would never put a $900 pistol.