M110 SASS

The M110 Semi-Automatic Sniper System (SASS) was developed by Knight's Armament Company from the company's SR-25 rifle. The system was designed to replace the bolt-action M24 Sniper Weapon System used by snipers, spotters, and designated marksmen in the United States Army. On September 28, 2005, Knight's Armament Company won the Semi-Automatic Sniper Rifle competition, and the weapon was designated the XM110. The rifle completed final operational testing in mid-2007 at Fort Drum, New York, with evaluations conducted by Special Forces personnel and soldiers from the 10th Mountain Division.

The rifle utilizes a gas-operated action with a closed rotating bolt and a Stoner bolt and carrier piston, feeding from a detachable box magazine. The design is based on the AR-10 layout but incorporates modifications intended to maximize parts commonality with the AR-15 and improve overall reliability. Ambidextrous controls include a double-sided magazine release, safety selector switch, and bolt catch. Unlike the earlier Mk 11, this model utilizes a modular rail system with an integrated folding front backup iron sight. The buttstock is fixed, featuring integral quick-detachable sling swivel sockets and an adjustable buttplate that can be positioned using a hand-tightened knob on the right-hand side. The barrel is equipped with a flash hider designed to host a quick-detachable sound suppressor, and the optics interface uses a one-piece scope mount.

The rifle entered active service in 2008, with its initial combat deployment occurring in Afghanistan with Task Force Fury. The United States Marine Corps also adopted the rifle to replace the Mk 11 and select M39 platforms. The weapon has seen use in conflicts including the Iraq War, the Syrian Civil War, and the Russo-Ukrainian War. Operators include the military forces of nations such as Poland, Georgia, Brazil, and Ukraine. Variants include the M110A2, which incorporates M-LOK rails, an altered gas system, a new suppressor, and an adjustable stock. The M110A3 variant is a conversion kit ordered in 2019 by NSWC Crane to upgrade USSOCOM rifles. The United States Army selected the Heckler & Koch M110A1 to replace the original system, though most fielded M110A1 units have been configured as squad designated marksman rifles.