The SR40 has much in common with its two predecessors. Its slide is machined from solid stainless steel, and it is the narrowest of any of its contemporaries. The slide also features very aggressive grasping grooves, making it easy to retract even with wet hands or when wearing gloves.
The front sights are mounted in dovetail cuts and are prominent, easy to acquire, and fast to line up while the rear sight is adjustable for elevation so that the pistol can be zeroed in for your preferred load.
When a round is chambered, a loaded chamber indicator rises above the slide, providing a visual and tactile indication of the pistol's condition. The tail of the striker is visible at the rear of the slide when the pistol is cocked. There's also a massive (well, I don't know how else to describe it) extractor with a large claw that ensures reliable functioning.
Locking is via the SR40's barrel hood, which rises up into and bears against the front of the ejection port. This holds the slide/barrel unit together until they recoil a short distance. The recoil makes the barrel cam down, allowing the slide to continue to the rear, extracting and ejecting the spent cartridge case. The dual recoil spring unit under the barrel then pulls the slide forward, feeding the next round from the magazine and pulling the slide/barrel unit into battery.
Made of glass-reinforced Zytel nylon, the SR40's frame is slimmer than much of the competition and has a grip frame angle that feels just like a 1911 pistol. The grip features impressed checkering on the side panels and frontstrap and the tacky feeling backstrap is grooved. Removing a single pin lets you reverse the backstrap to present either a flat or arched configuration (personally I prefer the latter). Lastly, the SR40's frame features a rail for mounting tactical lights and/or lasers.
The slide reciprocates on rails on a steel camblock—which also acts to cam the barrel down during movement—and steel inserts at the rear of the frame. This camblock also serves to disperse recoil pulse through the frame, lessening felt recoil. The SR40 is a striker-fired pistol, and as the slide goes forward into battery, the striker is held in a partially cocked position. Pulling the trigger through a full stroke draws the striker back completely, disabling the firing pin safety plunger and then tripping the sear to release the striker to fire the pistol.
Ruger's SR pistols are unique among today's plastic pistols in that they come standard with ambidextrous thumb safeties. While these are located flat against the frame to reduce the chance of them hanging up, they are serrated for positive manipulation. The SR40's port side bona fides are further enhanced by ambidextrous magazine release buttons.
Ruger kindly provided me with an early production SR40 to evaluate for POLICE Magazine. I was impressed with the pistol's balance and ergonomics. With the arched backstrap installed, the SR40 proved as naturally a pointing handgun as I have every handled.