The H&K M24, minus the suppressor and laser aiming module. Note the retention of the “USP Tactical” markings, and the second cut-out in the slide just ahead of the cocking serrations for the static slide lock.

The M24 is a .45 caliber handgun used by the United States military. An upgrade of Heckler and Koch’sTactical USP, the M24 is the standard-issue handgun for Marine Vent Infiltration Specialists, or “Vent Rats”, some of whom choose to carry it as a primary weapon when infiltrating ventilation systems, fitted with an optional suppressor. It is also an option for other Special Forces operators; Mark Drake and Trevor Wierzbowski of the 9th Regiment’s Reconnaissance In Force Team 1 both carried M24s, although Drake eventually returned his in favor of a Zastava M88A he captured in Romania.

Weapon Designation:Pistol, .45 Caliber, Semiautomatic, M24
Place of Origin:Germany
In Service:2044-present
Production History:
Manufacturer:Heckler & Koch GmbH
Weight:1.9 lb (0.861 kg) (plain)
3.23 lb (1.47 kg) (with suppressor and LAM)
Length:8.64 in (219 mm) (plain)
17.64 in (448 mm) (with suppressor)
Barrel Length:4.78 in (121 mm)
Cartridge:.45 H&K
Action:Short recoil
Rate of Fire:Semiautomatic
Muzzle Velocity:1,600 ft/s (488 m/s) with M45120D round
1,000 ft/s (305 m/s) with M45200P round
Muzzle Energy:682 ft/lbs (924 Joules) with M45120D explosive round
444 ft/lbs (602 Joules) with M45200P fluted round
Effective Range:50 m (55 yd)
Feed System:12-round detachable box magazine
Sights:Iron sights


By the 2040s, the United States military was faced with the prospect of having to fight and conduct covert operations on spaceships and space stations, and began training troops to use confined spaces such as vent shafts and access tunnels to their advantage. These specialized troops, formally known as “Vent Infiltration Specialists” and nicknamed “Vent Rats”, typically performed covert operations to gather intelligence, conduct sabotage, and support larger operations. Most were equipped with M41 submachine guns with a mounted suppressor. Although this allowed them to engage the enemy quietly, many Vent Rats voiced strongly vocal complaints about the size and weight of the M41, particularly with the suppressor attached.

Most Vent Rat missions focused on quiet infiltrations and minimal contact with the enemy, so whatever weapons they carried were normally only used for self-defense, and the M41 was felt to be excessive for this. After some consideration and a significant amount of feedback from many experienced Vent Rats, it was decided that the correct solution was not a long weapon of any type, but a handgun. A powerful handgun with an efficient suppressor would allow a Vent Rat much more freedom of movement in confined spaces than would be possible with a larger firearm, while still being adequate for defensive purposes and giving the user the capability to quietly ambush and eliminate enemy troops.

After some consideration, a list of requirements was drawn up for the new handgun and prototype entries were requested. In the end, a modified version of Heckler and Koch’s USP Tactical .45 was adopted as the M24. Only a few thousand M24s were initially accepted by the military, and because almost all of these were conversions of existing USP Tactical .45s, the M24 retained the “USP Tactical” markings; even after some of the pistols reached the end of their service life and began to wear out, newly-manufactured pistols were not given different markings and continued to be supplied to the US military with the “USP Tactical” markings.


The M24 is virtually identical to the USP Tactical .45, and has only three notable characteristics that make it stand out from the parent design.

1: The slide has a second cut-out just ahead of the cocking serrations on each side. A “static slide lock” is fitted to the gun on the opposite side of the regular slide lock. Like the S&W Mk 22 Mod 0 pistol, the static slide lock holds the slide in the forward position on firing, preventing the pistol from cycling. This helps to keep the weapon much quieter when fired with a suppressor because there is no open ejection port for gas to escape and because the spent casing is not ejected. This does, however, greatly limit the rate of fire, as after each shot, the slide block switch must be pushed into the downward position, the slide cycled by hand, and the slide block switch pressed up again. This also increases felt recoil significantly because the slide does not recoil and therefore the recoil spring does not absorb any of the firing force. On most M24s, which were conversions of pre-built USP Tactical .45s, the existing slides were simply modified by having the additional cut-out machined into them and then were refinished for full corrosion protection, which is why most M24s are still marked “USP Tactical”.

2: Although the M24 is capable of firing both .45 ACP and .45 Super, it is intended for use with the .45 H&K, which is nothing more than a variation on .45 Super with a slightly thicker casing. This results in lower internal capacity for propellant, but advancements in propellants allow the .45 H&K to be loaded in both a subsonic cartridge with similar performance to .45 ACP and a supersonic cartridge similar to .45 Super. The subsonic round, which weighs 200 grains, is intended for use with the suppressor and has a maximum muzzle velocity of 305 meters/second. The supersonic round weighs 120 grains, has a maximum muzzle velocity of 488 meters/second, and is intended for use when the weapon is not being used with the suppressor as the sonic boom from firing is less of an issue than when deliberately trying to be as silent as possible. However, it is entirely possible to fire the subsonic round without the suppressor or the supersonic round with it if necessary.

3: The M24 uses a suppressor and laser aiming module based on those used for the older Mk 23 pistol, which was very similar in design to the USP Tactical. Both were designed using the most advanced technology allowable under the Future Weapons Development Ban, and are significantly lighter and more effective than those made for the Mk23. The suppressor measures 35mm in diameter and 229mm in length, and weighs exactly one pound. Like the Mk23’s laser aiming module, the M24’s LAM has four different modes: visible laser dot sight, infrared laser dot sight, visible flashlight, and infrared flashlight. The infrared functions can only be seen when using night-vision goggles, as Vent Rats frequently do.

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