The Rise of the 9mm Luger
April 30, 2013
I had a ringside seat to a revolution — the 9mm Luger Revolution. Considering how long that cartridge had been around, the path to American acceptance was not as smooth as you'd suspect. In 1989 the 9mm Luger surpassed the .38 Special in ammo sales volume when many North American law enforcement agencies transitioned to semi-auto pistols.
The change was not painless, especially for the shooting sports industry. There were few 9mm Luger handguns built in the U.S. prior to that period. S&W had the Model 39 and its evolutionary spin-offs, and Colt offered its Government Model and Commander pistols in 9mm. That limited selection made it easy for ammomakers to create a limited line of 9mm ammo that worked. The fact that military-surplus 9mm pistols were finicky with U.S. ammo was usually written off to, "They're not built to commercial specs." However, law enforcement went with high-grade European pistols based on military designs, and that led to a lot of research to make the 9mm Luger the cartridge it is today.
Before the Revolution, a lot of U.S. 9mm Luger ammo was loaded on the "light" side. Winchester and CCI-Speer loaded 115-grain FMJ bullets, and Remington and Federal loaded 123- and 124-grain bullets but with the velocity reduced to accommodate the extra payload. A typical 115-grain load would make the nominal velocity of about 1,125 to 1,150 fps at well under the 9mm's maximum average pressure (MAP) of 35,000 psi; it was common for those loads to run about 26,000 psi. The 124-grain pressures ran a little higher, but seldom more than 30,000 psi.
Adding to the problem was the selection of noncanister propellants. When the 9mm Luger cartridge was a low-volume (and expensive) product, it was not economically feasible for many factories to inventory special propellants for it. Most 9mm Luger ammo was loaded with propellants that also worked well in the .38 Special.
In Europe, where the 9mm Luger cartridge has been refined over decades of military and police use, propellants were slower burning, and the 124-grain (8-gram) bullet was standard. The SIG, Beretta, and Glock pistols that made up the majority of U.S. police choices during the Revolution were developed around very different ammo than American factories were producing.
As 115-grain FMJ ammo was usually cheaper than the 124-grain domestic brews, many agencies used it for training ammo. In 1989 a big state police organization bought SIGs and ordered 115-grain practice ammo from CCI. Not long afterward I got a call from their training manager. The cartridge cases were trickling out of the SIGs and sometimes not completely ejecting. As I was investigating the detailed load records at our end, the manager called back with more news: His pistols would not work with any 115-grain ammo of U.S. make.
I had an option; we had developed a special 124-grain 9mm load for a European customer. We swapped out all the 115-grain stuff for the heavier bullet, and function returned to 100 percent.
The ammomakers here ramped up research into the new pistols. That meant buying a lot of test pistols for final acceptance function testing. It also meant developing propellants that better duplicated what the European pistols were accustomed to eating and working with bullet shape, cartridge overall length (COL), and profiles.
COL research helped a lot. The S&W and Colt 9mm pistols to which most pre-Revolution U.S. ammo was mated could deal with COLs well under the industry max COL of 1.169 inches. It was common to see COLs of 1.110 to 1.125 inches for FMJ-RN loads. Seating FMJs to the vicinity of 1.135 to 1.150 inches made for better feeding in the Euro pistols without causing issues with U.S.-built pistols.
Bullet COL and profile issues with expanding bullets could fill its own book, so I'll not cover that here. Suffice it to say that the very short 90- to 100-grain bullets whose profiles were optimized for the .380 Auto cartridge were miserable performers in Euro pistols because they loaded to about 1.005 to 1.050 inches. We dropped all 9mm Luger recommendations for 90- and 100-grain bullets from later Speer reloading manuals after the Revolution.
When I proposed a 9mm Luger 132-grain (8.5-gram) SWC-TMJ Match cartridge as a new Speer product, one of the engineering managers said that "9mm Luger Match" was an oxymoron. Indeed, for years this cartridge and its early pistols had never set any records for tiny groups. However, as we refined the TMJ to its final incarnations, we started seeing that some pistols could be very accurate.
The issue turned out to be a combination of bullet diameter specs and gun barrel diameter. I first encountered it when trying to load 0.355-inch cast bullets for my Browning Hi-Power. Even though cast from hard linotype, they were stripped of their rifling marks in-bore, leaving the bore heavily fouled. Keyholes were the rule. After digging all the lead out of the barrel, I measured the groove diameter at 0.357 inch. Switching the sizing diameter to 0.357 inch fixed that.
The U.S. spec for maximum 9mm Luger bullet diameter is 0.3555 inch. The barrel groove diameter spec is 0.355+0.004 — pretty loose. Fortunately, I've never found a barrel in a quality 9mm Luger pistol larger than 0.357 inch. The closer the bore diameter to 0.355 inch, the better accuracy you can expect. My custom Government Model 9mm has a box-stock Colt barrel with no special fitting. It can hold its own with most match-grade semi-autos. Its groove diameter is just under 0.3550 inch. My favorite load for it is the Speer 124-grain Gold Dot +P load. In the Colt's 5-inch barrel, it nearly equals the .357 Sig cartridge in velocity and muzzle energy.
Getting the 9mm Luger loaded with a wide variety of bullet weights and shapes to work in a disparate mix of firearms makes and models required unprecedented cooperation between the gunmakers and the ammo factories. It was worth it, because today this cartridge is far and away a superior product to what was made before about 1987.