A rail integration system is a generic term for a standardized system for attaching accessories to firearms. Rail systems are straight mounting brackets on the gun's receiver, handguard, or fore-end stock to allow sliding or variable-position attachments. An advantage of the multiple rail slots is the moveable positions to adjust for optimal placement of each item for a user's preferences, along with the ability to switch different items at different placements due to varying eye reliefs on gun sights.
A rail system mounted on top of a SIG SG 550
A dovetail rail on a rifle receiver for mounting a sight
A Romanian PSL rifle with a Warsaw rail
A French Army soldier armed with an Heckler & Koch HK416 with multiple rail-mounted attachments, including a scope, a tactical light, and an M320 underbarrel grenade launcher
A sniper rifle is a high-precision, long-range rifle. Requirements include high accuracy, reliability, and mobility, concealment, and optics, for anti-personnel, anti-materiel and surveillance uses by military snipers. The modern sniper rifle is a portable shoulder-fired rifle with either a bolt action or semi-automatic action, fitted with a telescopic sight for extreme accuracy and chambered for a high-ballistic performance centerfire cartridge.
The bolt-action 7.62×51mm M24 Sniper Weapon System is capable of 0.5 MOA accuracy to maximal effective range of about 800 meters. The M24 was the United States Army standard-issue sniper rifle from 1988 to 2010.
German sniper aiming his Karabiner 98k with 4×36 Zeiss ZF39 telescopic sight.
Vietnam War era sniper rifles, US Army XM21 (top) and USMC M40 (bottom)
U.S. Marine Corps SRT sniper team with an M24 sniper rifle, during sniper training