By Kyle Mizokami, The National Interest
The 9mm Luger, invented before the Great War, is one of the longest serving gun calibers in history. Introduced in 1901, it has served in virtually every conflict since then up until today. From World War I’s German army to the British army fighting ISIS in Syria, the Luger round has served militaries for over a century. Despite its age, the 9mm is more dangerous than ever before, due to innovations in ammunition lethality that squeeze greater performance out of the bullet.
Adequately powerful and compact, the 9mm Luger round received newfound popularity in the 1980s when the so-called “Wonder Nine” pistols upended the dominance of revolvers and large caliber handguns on the U.S. market. It is the standard handgun caliber for NATO members, with many armies on their second or third generation 9mm pistol, and was recently re-adopted by the U.S. Army for its new issue M17 Modular Handgun System. The 9mm Luger round will be around for many more years. Here are five of the best guns the round is used in.
The Glock 19  was one of the first Glock variants produced. Released in 1988, it was basically the same handgun albeit with a shorter barrel and grip. This reduced the magazine capacity from seventeen rounds to fifteen, but also produced a pistol that was easier to conceal. Today, it is generally acknowledged among handgun enthusiasts as the best Glock model for all-around use. The Glock 19 has been adopted by the U.S. Navy SEALs, U.S. Army Rangers and a modified version competed for the U.S. Army’s Modular Handgun System competition.
The Glock 19 has an overall length of 7.36 inches and a barrel length of 4.01 inches. It is a double-action pistol, meaning that after a round is chambered the pistol only requires pulling the trigger to set the firing pin and fire. Subsequent shots will also only require a single trigger pull. This eliminates the need to cock the hammer prior to firing but does introduce a slightly longer trigger pull. The basic Glock design incorporates three safeties, including a firing pin and drop safety, as well as a trigger safety. It does not have an external manual safety mechanism.
The Sig P226 was originally developed from Sig Sauer’s P210 pistol as a replacement for the long-serving .45 ACP 1911A1 handgun. The resulting pistol failed to win the contract, which went to the Beretta M9 instead. Although the U.S. Navy also picked up the Beretta, early problems with metal quality resulted in cracked slides among pistols with high round counts. SEALs, who experienced defect-related accidents, turned to the Sig P226 instead, calling it the Mark 11. Adoption by U.S. police forces further raised the P226’s profile.
The P226 is an all metal handgun with a metal frame. It has a fifteen-round magazine, an overall length of 7.72 inches, and a barrel length of 4.11 inches. Loaded, the gun has a weight of 2.28 pounds. Like the Glock 19 the P226 is also a double action pistol, although it also has a single action mode allowing the pistol to be manually cocked. It also features a decocking lever to lower the hammer without pulling the trigger.
Heckler & Koch VP9
One of the newest 9mm Luger handguns is the Heckler & Koch VP9. Introduced in 2014, the VP9  is like the rest of the handguns on this list a high capacity, twin-stack handgun with a steel slide and polymer frame. The VP9 carries up to fifteen rounds—as many as a Glock 19. This German-designed pistol has dimensions similar to the G19 and P226 and uses a cold hammer forged barrel for increased accuracy and barrel life.
Unlike older pistols that utilize a hammer, the VP9 is a striker-fired pistol. Striker-fired pistols use a spring-loaded firing pin that is partially cocked by pulling back and releasing the slide. Pulling the trigger completes the cocking action and releases the firing pin. As a result, striker fired pistols are immune to any accidental discharge that does not involve pulling the trigger—such as dropping the handgun on a hard surface.
A new feature—increasingly common in handguns—of the VP9 is the ability to tailor the pistol’s grip to a wide variety of hand sizes. Each pistol comes complete with a number of removable backstraps and grip panels to reduce or enlarge grip width, with a total of twenty-seven different size configurations available for small to large hands.
Smith & Wesson M&P
The Smith & Wesson M&P (Military and Police) was first introduced in 2005 and as a hybrid of two previous guns, the Sigma and the SW99. Like the rest of the guns on this list, it has polymer frame and steel slide, a large internal magazine (seventeen rounds) and a striker-fired operating system. The M&P  has aggressive good looks, with serrations on the slide to promote a better grip, and a built-in Picatinny rail under the barrel for mounting lights and laser pointers.
Smith & Wesson claims that the M&P’s low bore axis reduces muzzle rise and allows the shooter to get back on target faster. In many respects it is similar to the Glock 17—including magazine size—but one reviewer has pointed  out that it is slightly larger and heavier. The M&P also features a loaded-chamber indicator which tilts upward when a round is in the chamber, ambidextrous controls and four interchangeable palm swell inserts of different sizes to accommodate different hand types.
Originally developed in Croatia as the HS2000, the Springfield XD  (“Extreme Duty”) handgun has enjoyed considerable success in the United States. The XD externally resembles a Glock, from nearby Austria, though is somewhat blockier in appearance. The standard service model features a four-inch barrel—par for the course on this list—and a double-stack magazine that holds up to sixteen rounds of 9mm Luger ammunition.
The Springfield XD combines a number of older and newer features from other guns on this list to create a fairly unique and impressive package. The XD has a grip safety like the one on the Colt 1911A1 handgun, that prevents the gun from being discharged unless gripped properly. It also features a trigger safety, like the Glock, a drop safety that prevents the striker from being released, and a loaded chamber indicator like the Smith & Wesson M&P. A flip of a lever allows the pistol to be quickly field stripped for cleaning.
Kyle Mizokami is a writer based in San Francisco who has appeared in The Diplomat, Foreign Policy, War is Boring and The Daily Beast. In 2009 he cofounded the defense and security blog Japan Security Watch. You can follow him on Twitter: @KyleMizokami .