- "Fully automatic pistol. Incorporates recoil-mitigation technology."
- — Description.
The KAP-40 is used by the Mercs as a sidearm. KAP-40s are scarce throughout the campaign. The KAP-40 is unlocked for the player's use following the completion of "Fallen Angel", and equipped with a Suppressor is the recommended secondary weapon in the mission "Karma". One with a Reflex Sight is used to dispose of the Mercs on the dance floor of Club Solar during a slow-motion sequence later in the mission. The player can complete a challenge for this mission by obtaining five headshots during this sequence.
At the end of "Judgement Day", Section will take a KAP-40 from the corpse of a Merc and use it to kill two other Mercs who are protecting Raul Menendez, one of which may be DeFalco if he has survived up to that point.
In multiplayer, the KAP-40 has a high rate of fire with manageable recoil at close quarters engagements. At longer ranges, the recoil is harder to control. The KAP-40's small 15-round magazine also means that the player will need to reload often. With the Extended Clip attachment, the magazine size is increased to 20 rounds. Also, with Dual Wield, the weapon can be devastating, but the hipfire accuracy is rather inaccurate, even though the damage is higher than most pistols at range. After a recent patch, the KAP-40 range has been toned down to make the weapon more of a close quarter's weapon. The same occurred with the B23R. The KAP-40 can be a great backup for snipers and other long-range playstyles. Despite the weapon's high rate of fire and high damage, it is an uncommon weapon online due to the high level unlock.
The KAP-40 is the second weapon tier on Gun Game, where it is equipped with the Dual Wield attachment. It is the main weapon of One in the Chamber, where it is semi automatic, It is also featured in the Pre-Made-Class, Scout recon, where it is equipped with Dual Wield. It can also appear in Sharpshooter, with any Attachment.
- Reflex Sight (unlocked weapon level 2)
- Extended Clip (unlocked weapon level 3)
- Laser Sight (unlocked weapon level 4)
- Long Barrel (unlocked weapon level 5)
- FMJ (unlocked weapon level 6)
- Fast Mag (unlocked weapon level 7)
- Suppressor (unlocked weapon level 8)
- Tactical Knife (unlocked weapon level 9)
- Dual Wield (unlocked weapon level 10)
The KAP-40 appears in Zombies, available from the Mystery Box for 950 points. It has a 12-round magazine and a high rate of fire. Its usefulness drops after early rounds because of its low reserve ammo and small magazine. When Pack-a-Punched, it becomes the Karmic Atom Perforator 4000 and gains a 15-round magazine. In the game mode Turned, it is the fifth weapon to be obtained if the player is a human.
- The KAP-40's serial number is KS702832.
- The KAP-40 is semi-automatic in a few occasions:
- In "Cordis Die", where it can be picked up after being hit by the truck (Samuels and the LAPD officers also use semi-auto KAP-40s in this mission)
- At the end of "Judgment Day", when Section uses it to kill two Mercs
- In "FOB Spectre", by a playable Navy SEAL in the victory cutscene
- In "Dispatch" to assassinate Tian Zhao
- In One in the Chamber.
- It has a QR code painted on its left side, which is clearly visible when wielding it, and slightly visible in the Create-a-Class menu.
- The numbers .45 ACP is engraved on the side of the gun.
- The right side of the gun is a mirror image of the left side, with an ejection port added. Assuming this is intentional, this makes the weapon ambidextrous.
- When dry reloading with Dual Wield or a Tactical Knife, the character will re-chamber the weapon by pressing the bolt release instead of pulling the slide.