- "This is a weapon of war. It's made to kill your enemy."
- ―Jack O'Neill
It was selected as a standard issue weapon, because it offered better armor-penetrating and killing power than the 9mm Heckler & Koch MP5 it replaced. Like other firearms, it is technologically primitive compared to Goa'uld, Wraith, and Ori weapons, but it is more than capable of piercing the armor worn by Jaffa, Ori soldiers, and Wraith warriors. According to Jack O'Neill, it is a weapon of war, designed to kill the enemy, and holds better offensive capabilities than the staff weapon, which he said was designed primarily to intimidate (SG1: "The Warrior").
The SGC uses the Standard P90, distinguished by the angular-cut sight. Contrary to popular belief, the P90 does not have an integral red-dot sight (an aspect that was present on the Tokyo Marui P90), but rather a day/night sight that offers two different graticules; the first was circular and colored white, while the second, the night-time sight, was an 'open-T' design which glowed red via use of tritium. Depending on light conditions, the sight would automatically adjust or fade between the two graticules, granting the user a reliable aiming reference at all times. This is the original variant as issued in the SGC.
In reality, the day-time 'white-sight' was eventually made black as the original design had a tendancy to wash-out against sunlight during the daytime. The sight changes were suggested by the US Secret Service, who issues it as apart of their standard arsenal. The sight module was/is manufactured by Ring Sights and is noticeably rectangular, with a blue lense-face.
Other features of the SGC P90 are two mounting rails on either side of the upper receiver. Using these rails, accessories (such as a Kull disruptor, visible lasers, or flashlights -- which are commonly shown on nearly every weapon) can be attached and utilized as apart of the weapon itself.
Other accesories available to the P90 platform are sound suppressors (used in conjunction with subsonic ammunition; Sb193 5.7mm x 28), an integral laser aiming system (made by Laserex; a permanent modification to the lower receiver requiring the installation of an activation button, battery case and cover, and the laser module itself -- available in visible or infrared wavelengths), and magazine clamps to double one's active ammunition supply without having to dig out a magazine from a pouch, enabling a faster reload time. The P90 accepts a wide variety of AR-15/M16/M4 aftermarket flash hiders as well, each with its own advantages (if only aesthetic). Other variants include the Triple Rail and Tactical models, each offering upper receiver rails in place of an integral sight. This feature permits the usage of various optics ranging from dot-sights to telescopic sights. The Triple Rail features no iron sights whatsoever, while the Tactical features emergency iron sights.
Within the SGC and Atlantis, they are typically either black or olive green, although a gold variation was also in use around two years after the destruction of the Ori.
- The P90 is classified as a Personal Defense Weapon (PDW). It is a class of weapon designed for close-range self-defense by support troops, gunners, and vehicle crews or use in Close Quarter Battle by commandos and anti-terrorist / hostage rescue teams.
- Major Samantha Carter erroneously describes the P90's rounds as being "teflon-coated" (SG1: "The Warrior") when they are actually copper-jacketed. Though this need not be in error, armor piercing brass bullets are coated, sometimes with teflon, to reduce barrel wear.
- One of the reasons the "Carter Special" was created was to address a shortage of P90 blanks during Season 7. According to an interview with Amanda Tapping, this was due to the increased demand for P90 ammo during the invasion of Iraq.
- The P90 was the standard issue right until the last season of SG-1 and Stargate Atlantis.