Remington R51

Pedersen's layout of the Remington R51 is copied in the Walther PPK pistol using a stationary barrel and recoil spring surrounding the barrel.[8] However, a notable design feature is the use of a locking breech block within the slide utilizing the "hesitation-locked" action originally developed by John Pedersen.[3][9] When the pistol is in battery, the breech block rests slightly forward of the locking shoulder in the frame. When the cartridge is fired, the bolt and slide move together a short distance rearward powered by the energy of the cartridge as in a standard blowback system.[8] When the breech block meets the locking shoulder, it stops, locking the breech.[8] The slide continues rearward with the momentum it acquired in the initial phase.[8] This delay allows chamber pressure to drop while the breech remains locked and the cartridge slightly extracted. Once the bullet leaves the muzzle and pressure drops away, the rearward motion of the slide lifts the breech block from its locking recess through a sliding cam arrangement, continuing the operating cycle. Only manually retracting the slide with the grip safety held in, or firing a cartridge opens the pistol.

Because the action halts cartridge extraction momentarily while holding locked the breech, the R51 is designed to use higher pressure cartridges than a straight blowback firearm with similar slide weight.[3][8][9] The hesitation-locked Model 53 was based on the Model 51 design, and was built by Remington in .45 ACP for Navy trials. The Pedersen design has the recoil spring surrounding the barrel, reducing the pistol's overall profile.[9] Lighter operating parts and longer lock time provide less felt and actual recoil.[9] The R51's low bore axis gives less muzzle rise which also lowers perceived recoil, while the stationary barrel improves accuracy and simplifies construction.[3][8][9]

Like the original the new Remington R51 uses an internal hammer with a built-in drop safety and features a single-action trigger.[8][10] The slide stop is mostly recessed into the left side of the frame. The primary safety is a grip safety which must be depressed before the pistol will fire.[3][10] The R51 lacks the magazine safety that was present on the original model 51. The trigger guard is undercut to allow a higher grip on the frame.[9] The frame has a 20-degree grip angle designed for natural point shooting, and has checkering on the front strap for improved grip of the gun.[3][8][9] The R51 comes standard with polymer grip panels which are held on with conventional screws. Remington plans to offer optional rubber and rosewood grip panels as accessories for users desiring a wider, more hand-filling grip.[3][9] The magazine is a steel single-column design with a polymer floorplate. Capacity is 7 rounds in 9×19mm.[2][9] The magazine release is ambidextrous. The slide of the R51 is machined from stainless steel and has a matte black FNC finish, while the frame is machined from 7075 aluminum alloy and has a matte black anodized finish[3][10] The 3.4" barrel is machined from 416 stainless steel and has a bright finish.[3][9][10]

A press release from Remington in July 2014 said that production of the R51 had been suspended and was expected to resume in October. Customers had informed Remington "that some R51 pistols had performance issues" some serious.[11] Remington determined that these "performance problems resulted from complications during our transition from prototype to mass production."[11][12] In June 2016, Remington announced it was ready to ship new pistols to those who had returned their R51s for repair and / or replacement.[13]

A review in thetruthaboutguns.com said the Remington R51 was an “epic fail,” noting “To its credit, the R51 didn’t seem to have any issues with liking one brand of ammunition over another. It malfunctioned equally with all of them.”[14][15][16]

• Official website
  • Remington R51 pistol owner's manual