P90 phaser rifle

The P90 phaser rifle is the standard phaser rifle for SG-1 since the mission to P3X-888, as well as the standard issue weapon for the Atlantis Expedition.

Overview
It was selected as a standard issue weapon because it offered better armor-penetrating and killing power but it is more than capable of piercing the armor worn by Jaffa, Ori soldiers, and Wraith warriors. According to Colonel 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. The P90 is superior in combat against staff weapons due to their rapid firing rate and precision. They can easily penetrate the armor of a Jaffa, killing them.

Stargate Command uses the standard P90, distinguished by the angular-cut sight. Contrary to popular belief, the P90 does not have an integral red-dot sight, but rather a day/night sight that offers two different reticles; 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.

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, Naquadah powered lasers, or flashlights which are commonly shown on nearly every weapon can be attached and utilized as a part of the weapon itself.

Within the SGC and Starbase 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.

History
Although the P90 has been standard SGC issue since 2363, Dr. Daniel Jackson and Typhuss James Kira have only begun using the weapon in recent years. Up until that point Typhuss used a type 2 phaser and Dr. Jackson utilized a type 2 phaser.

When the Odyssey was overcome by Replicators, Colonel Samantha Carter and Major Kevin Marks used P90s to keep the Replicators bay and to stop them from gaining access to the Asgard computer core.