Starting in the early 2000s, the rapid growth of legislation and regulations allowing concealed carry by law-abiding citizens in various jurisdictions created a large market for handguns manufactured specifically for such use. Desirable characteristics for firearms of this type include: small size, thinness, high magazine capacity, lightweight construction (often achieved through the use of polymer frames), stealthy darkened stainless steel slides, high visibility and/or night sights, and large ergonomic ambidextrous manual thumb safeties and magazine releases. Ruger specifically designed the SR9 pistol to address the very active and profitable concealed-carry handgun market segment and it possesses the majority of the aforementioned attributes.
The SR9 is the first large-caliber striker fired pistol designed and manufactured by Sturm Ruger. Similar to Glock's "safe action", the striker fired SR9 features a pre-set trigger. With this type of action, the striker is partially cocked when the slide is cycled, then is fully cocked and released when the trigger is pulled. Contrary to popular belief, the Ruger SR9 is not a Glock copy like the SIGMA, and is an entirely new design. Due to safety concerns, the moderately long and heavy trigger pull of this type is seen as ideal for law enforcement and self-defense applications. The SR9 and SR9c have an identical trigger group. Enthusiast website Gunblast rated both the SR9 and SR9c examples it tested with a factory trigger rearward travel at 9.5 mm (0.37 in). Gunblast rated its SR9 example with and trigger pull of 30 N (6.7 lbf), and Gunblast rated its SR9c example with a trigger pull of 23 N (5.2 lbf).
The SR9 is recoil operated with a locked breech. It features a staggered column box magazine (double-stack magazine) with a capacity of 17 rounds, and is also available in a 10 round configuration for locales where capacities are restricted. The pistol has a very low slide profile; this holds the barrel axis close to the shooter's hand and makes the Ruger SR9 more comfortable to shoot by reducing muzzle rise and allowing for faster aim recovery in rapid shooting sequences. The slide is available in either brushed or blackened through-hardened stainless steel, and the frame is fiberglass-reinforced nylon polymer, resistant to warping or failure. The frame is offered in black or olive drab. The SR9 also has a reversible backstrap which allows the owner to select either a flat or arched grip housing, based on personal preference. In addition, the SR9 sports a Picatinny rail for the mounting of laser sights and tactical lights. The SR9 boasts multiple safety devices such an ambidextrous manual thumb safety and magazine release, a loaded chamber indicator, a visual and tactile cocked-striker indicator, and a firing pin block safety which prevents the pistol from firing if it is accidentally dropped. The SR9 also features a magazine disconnector safety The Ruger SR9 can safely be dry fired with an empty magazine in the pistol. A Ruger-issued warning states that, due to the disconnector, dry firing the pistol without the magazine inserted will cause unnecessary wear to the striker block, but published firearms industry information notes that the SR9's disconnect can be deactivated simply by removing some of the disconnector linkage.
The SR9's open iron sights are of the three-dot enhanced contrast variety, and offer drift adjustment on both front and rear blades for windage, as well as rear-sight adjustment for elevation. The Ruger SR-series factory accessories consist of spare magazines, a grip adapter and a tool to aid loading. Other manufacturers offer after market accessories like handgun holsters in various configurations and alternative contrast enhanced sight lines like self-illuminating tritium night sight elements and fiber optic sight elements for the Ruger SR-series.
The SR9c is lighter and dimensionally smaller compared to the SR9, but it has the same grip width (measured across safety levers) as the full-sized SR9. Contrary to popular belief, the SR9c was designed from the ground-up to be a new design rather than just a scaled-down SR9. The manual safety, adjustable rear sights, and updated version of the trigger are all present in the compact version also. In contrast to the SR9 recoil spring assembly the SR9c pistols are fitted with a dual recoil spring assembly. The SR9c is normally supplied with two magazines. The standard 10 round compact magazine features a flat bottom floor plate, with an extended floor plate also included. The second magazine is a full-size 17 round unit featuring a grip adapter that transforms the short compact SR9c grip into a full-sized grip. However, in jurisdictions where the number of rounds in a firearm are limited by law the SR9c is shipped from Ruger with two 10-round magazines and two extended floor plates. Additional retraction grooves (serrations) are located on the front sides of the SR9c slide, making it easier to operate and press-check the slide. The Ruger SR9c was chosen as the Shooting Industry Academy of Excellence's Handgun of the Year in 2010.