Notes: The DP-51B is the standard sidearm of the South Korean armed forces, and is called the K-5 by the ROK military. It is often market to civilians under the name of the FastFire.

The DP-51 is in many ways standard for a modern 9mm pistol – it has a high-capacity magazine, a modified Browning short-recoil operation (in fact, quite similar to the HP-35 High-Power), and a medium-length barrel. However, the trigger mechanism is unusual. Known as 3H (High-accuracy first shot, High-speed shot, High-reliability), the trigger mechanism was first developed by FN in the late 1970s, but was rejected at the time as being too complex and expensive to produce in large numbers.

3H allows the DP-51 to be loaded normally and then decocked normally, like any other double-action pistol. However, during loading, as the slide is pulled back and released, a return spring for the hammer is compressed, staying that way when the DP-51 is decocked. This allows that first double-action trigger pull to feel more like a light single-action trigger pull, allowing for a much faster and more accurate follow-up shot. The pistol must simply be cocked and the hammer lowered to allow a rapid shot with minimal recoil. Trigger pressure required is cut in half as opposed to normal double action actuation. The sights are luminous and white for low light shooting. Of course, the DP-51 may also be used as a standard double-action pistol, or even a single-action pistol. Unusually for a pistol built to be a military service weapon, the DP-51 uses a light alloy frame instead of steel. Standard barrel length for the DP-51 is 4.1 inches, but a compact version, the DP-51C uses a 3.6-inch barrel and a shorter grip. Another variant, the DP-51S, uses the DP-51B’s frame, but the shorter DP-51C’s barrel and slide.

The DP-51 uses an ambidextrous manual safety, but this safety has the problem of being difficult to return to the safe position without having to shift one’s grip on the weapon. In addition, left-handed shooters will find that safety on the right side is much smaller than that on the left side. Some other complaints include the sights; they are of the three-dot type, but most shooters find the rear notch to be too wide for quick shots, and the three white dots are large enough to be distracting. The front sight is also considered by many shooters to be too low.

The DP-51 has spawned several other variants, primarily for the civilian market. The DP-40 (also called the DH-40) is a DP-51B chambered for the .40 Smith & Wesson cartridge. It is mostly aimed at the civilian market, but also popular with South Korea’s National Police (the KNPs). The DP-45 (also called the DH-45) is also the same, but chambered for .45 ACP; the DP-45 had several teething problems due to the light alloy frame and the powerful .45 ACP cartridge. This caused the withdrawal of the DP-45 from the market after only a few weeks, until some frame strengthening was done; this improved DP-45 is often referred to as the DP-45 Mark II.

Twilight 2000 Notes: Only the DP-51B, DP-51C, and the DP-51S exist in the Twilight 2000 timeline.