Ruger Revolver Serial Number Hub

The Security Six represented a watershed moment for Sturm, Ruger & Co. when it debuted in 1972 as the company's first double-action revolver. Chambered primarily in .357 Magnum (with .38 Special and 9mm variants following), the Security Six was designed from the ground up to be a duty-grade sidearm capable of withstanding the rigors of daily law enforcement carry. Its relatively compact frame, available in 2.75-inch, 4-inch, and 6-inch barrel configurations, made it versatile enough for plainclothes work, uniformed patrol, and sporting use alike. Police departments across the United States adopted the Security Six throughout the 1970s, cementing Ruger's reputation as a serious contender in the service revolver arena.

The Security Six shared its serial number prefix block (150–162) with two companion models: the Speed-Six (a round-butt, fixed-sight variant optimized for concealed carry) and the Police Service-Six (a fixed-sight duty model). Together, this trio gave Ruger a complete law enforcement product line. Production continued robustly through 1985, when the introduction of the GP100 signaled the beginning of the end for the Security Six family. The last Security Six revolvers were shipped in 1988, closing a sixteen-year chapter. Today, well-preserved examples — particularly the scarce 2.75-inch barrel models and the less common 9mm variant — are increasingly sought by collectors who appreciate the Security Six as the revolver that proved Ruger could compete with Smith & Wesson and Colt on their home turf.

The GP100 arrived in 1985–1986 as the natural evolution of the Security Six, engineered from the outset to be the strongest medium-frame double-action revolver on the market. Where the Security Six had proven itself reliable, Ruger's engineers sought to build a platform that could handle an unlimited volume of full-power .357 Magnum ammunition without the frame-stretching concerns that plagued lighter designs over tens of thousands of rounds. The result was a heavier, more robust revolver featuring a triple-locking cylinder for superior lockup, a modular peg-style grip system that allowed shooters to customize ergonomics without a gunsmith, and an overall design philosophy that prioritized longevity above all else.

In the decades since its introduction, the GP100 has expanded far beyond its original .357 Magnum/.38 Special chambering. Ruger has added variants in .327 Federal Magnum, 10mm Auto, .44 Special, and a popular 10-shot .22 LR model — transforming the GP100 from a single-purpose duty revolver into a versatile platform serving target shooters, handgun hunters, and collectors alike. Specialty models like the Match Champion (introduced around 2012) brought competition-grade features to the line. Still in production today, the GP100 stands as one of the longest-running and most respected double-action revolvers in American firearms history, and early-production examples from the 170-prefix serial range are beginning to attract dedicated collector interest.

The Ruger Blackhawk burst onto the American firearms scene in 1955, born from the postwar fascination with the frontier West and the enduring appeal of the single-action revolver. Bill Ruger recognized that shooters craved the look and feel of the classic Colt Single Action Army but demanded modern metallurgy and engineering capable of handling contemporary magnum cartridges. The original Blackhawk, chambered in .357 Magnum, delivered precisely that — and within a year, Ruger introduced a .44 Magnum variant that arrived on dealer shelves nearly simultaneously with Smith & Wesson's legendary Model 29, making the Blackhawk one of the very first production revolvers chambered for that thundering cartridge.

Collectors divide Blackhawk history into distinct eras defined by both design and safety mechanism. The earliest guns (1955–1962) are known as "Flat-Top" models, identified by the absence of protective ear guards on the rear sight — these are the rarest and most valuable production Blackhawks. From 1962 through 1972, the "Three-Screw" era saw the addition of a redesigned top strap and frame, identifiable by three visible screws on the left side of the frame. These pre-1973 revolvers lack the transfer bar safety that would define all subsequent production, making them both mechanically distinct and highly prized by collectors who value original-condition firearms.

In 1973, responding to concerns about the traditional single-action mechanism's vulnerability to accidental discharge if dropped on a loaded chamber, Ruger implemented a voluntary recall and conversion program. The company offered to retrofit all existing "old model" Blackhawks with a new transfer bar safety mechanism free of charge — a program that remains active to this day. The "New Model" Blackhawk, introduced in 1974 with the transfer bar built in from the factory, became the standard and continues in production through the present. Unconverted old models that retain their original mechanism are the most desirable to serious collectors, though they require disciplined safe-handling practices. The Bisley variant, introduced in 1986 with its distinctive grip shape and lowered hammer, added yet another chapter to the Blackhawk's rich collector legacy.

The revolver shown throughout this section is Greg Cook’s own 1957 Ruger Flat Gate Single-Six. Every photograph documents the same early rimfire single-action revolver from a different angle. It is not a Blackhawk, GP100, Security-Six, or later New Model Single-Six. Keeping that distinction clear matters because early Ruger single-actions can look similar at a glance while differing substantially in frame details, loading-gate construction, sight arrangement, grip hardware, serial-number format, and safety mechanism.

This revolver belongs to the early Single-Six story that began in the 1950s, when Ruger adapted the traditional western single-action form to a modern .22 rimfire platform. The example photographed here carries serial number 15872, visible on the left side of the frame in several views. That plain, non-prefix serial format is consistent with early production. Ruger’s historical serial tables should still be treated as approximate first-shipped-year references rather than exact assembly dates, but the number places this revolver within the early collector period and supports its identification as a 1957 example.

The “Flat Gate” name refers to the early loading gate design. On these revolvers, the gate is visually flatter and simpler than the later rounded or contoured gate used on subsequent Single-Six production. That feature is one of the most useful visual clues, but it should never be considered in isolation. A careful identification also examines the unprefixed serial number, frame screws, fixed sights, grip-frame profile, cylinder markings, ejector-rod housing, barrel contour, and the exact Ruger rollmarks.

Serial number, frame screws, and originality clues

The left-side photographs are the most useful images for dating and identification because serial number 15872 is visible on the frame. The absence of a later hyphenated prefix is important. Ruger adopted prefix systems as production expanded, so collectors should record the number exactly as stamped rather than adding punctuation or assuming missing digits. An early plain-number Single-Six belongs to a different dating system from later New Model revolvers.

These views also show the screw arrangement associated with Ruger’s early single-action lockwork. The visible screws help distinguish an Old Model action from the later transfer-bar New Model system. Because external appearance can be altered, a collector evaluating a purchase should confirm that the revolver has not received a later safety conversion, replacement grip frame, non-period cylinder, refinished surfaces, or mismatched screws. Factory work is not necessarily undesirable for a shooter, but it can affect collector interest when originality is the goal.

Sight, barrel, cylinder, and loading-gate inspection

The top and front three-quarter photographs document details that a side profile can hide. The fixed sight arrangement is visible along the barrel and top strap. The cylinder-to-frame relationship, hammer shape, barrel contour, and ejector-rod housing can all be compared with known early Single-Six configurations. These views are also useful when looking for uneven gaps, altered sights, bent ejector housings, or refinishing that has softened stampings and edges.

The loading gate deserves special attention because it gives the Flat Gate variation its familiar collector name. The gate should be examined directly from the appropriate angle and compared with a documented early example. A photograph alone cannot establish mechanical condition, and no visual feature substitutes for checking timing, lockup, bore condition, chambers, firing pin, and safe operation. A qualified gunsmith should inspect an older revolver before it is fired when its service history is unknown.