
The M110 Semi Automatic Sniper System (M110 SASS) is an American
semi-automatic sniper rifle
A sniper rifle is a high-precision, long range shooting, long-range rifle. Requirements include high accuracy, reliability, mobility, concealment, and optics, for anti-personnel weapon, anti-personnel, anti-materiel rifle, anti-materiel and sur ...
that is chambered for the
7.62×51mm NATO
The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless, straight walled, bottlenecked, centerfire rifle cartridge. It is a standard for small arms among NATO countries.
First developed in the 1950s, the cartridge had first be ...
round. It is manufactured by
Knight's Armament Company, developed from the
Knight's Armament Company SR-25, and adopted by the U.S. military following the 2005 US Army Semi-Automatic Sniper Rifle (XM110 SASR) competition.
The M110 is to be replaced by the lighter and more compact
M110A1 CSASS, which is developed from the G28, a variant of the
Heckler & Koch HK417; however, most M110A1 models fielded have been of the SDMR variant. In 2021, a newer variant, the M110A2, was showcased and seen in use in early 2022.
History

The M110 Semi-Automatic Sniper System is intended to replace the
M24 Sniper Weapon System
The M24 Sniper Weapon System (SWS) or M24 is the military and police version of the Remington Model 700 rifle, ''M24'' being the model name assigned by the United States Army after adoption as their standard sniper rifle in 1988. The M24 is ref ...
used by
sniper
A sniper is a military or paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with telescopic si ...
s,
spotters,
designated marksmen, or squad advanced marksmen in the
United States Army
The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...
. However, the U.S. Army still acquired M24s from Remington until February 2010.
On September 28, 2005, the Knight's Armament Co. rifle won the competition and was selected to be the supplier of the M110 Semi-Automatic Sniper System.
The XM110 underwent final operational testing in May and June of 2007 at Fort Drum, New York by a mix of Special Forces troops and Sniper trained soldiers from the 10th Mountain Division. In April 2008, U.S. Army soldiers from Task Force Fury in
Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...
were the first in a combat zone to receive the M110. The troops rated the weapon very highly, noting the quality of the weapon and its semi-automatic capabilities compared to the bolt-action M24. The
United States Marine Corps
The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionar ...
will also be adopting the M110 to replace some
M39 and all
Mk 11 as a complement to the
M40A5.
The rifle has
ambidextrous
Ambidexterity is the ability to use both the right and left hand equally well. When referring to objects, the term indicates that the object is equally suitable for right-handed and left-handed people. When referring to humans, it indicates that ...
features such as a double-sided magazine release, safety selector switch, and bolt catch.
Design and features
The rifle is similar to the
SR-25/Mk 11 Mod 0, but differs significantly in
buttstock and rail system design. The SR-25, Mk 11 Mod 0, and M110 are based loosely on the original
AR-10
The ArmaLite AR-10 is a 7.62×51mm NATO battle rifle designed by Eugene Stoner in the late 1950s and manufactured by ArmaLite (then a division of the Fairchild (aircraft manufacturer), Fairchild Aircraft Corporation). When first introduced in 1956 ...
developed by
Eugene Stoner
Eugene Morrison Stoner (November 22, 1922 – April 24, 1997) was an American machinist and firearms designer who is most associated with the development of the ArmaLite AR-15 rifle that was redesigned and modified by Colt's Manufacturing Compan ...
but feature additional refinements instituted by KAC to maximize parts commonality with the
AR-15 design, improve weapon reliability, and increase accuracy.
The main differences between the Mk 11 and M110 are improvements suggested by a user group meeting between NAVSPECWAR, USASOC and USA in 2007:
* The rail system used: the KAC Free Floated RAS on the Mk 11 is replaced by a URX modular rail system with integral folding front 600-meter backup iron sight.
* The M110 buttstock: fixed, though the buttplate is adjustable for
length of pull to match user preferences. Adjustment can be made without tools via a notched hand-tightened knob on the right-hand side of the stock. This feature was added during the change from XM110 to M110. The fixed buttstock also features integral quick-detachable sling swivel sockets located on each side of the stock near the rear of the lower receiver.
* The addition of a flash hider to the barrel of the M110, which also necessitates a modified QD Suppressor unit similar to that on the Mk 11.
* The M110's use of KAC's one-piece 30 mm
scope mount
Scope mounts are rigid implements used to attach (typically) a telescopic sight or other types of optical sights onto a firearm. The mount can be made integral to the scope body (such as the Zeiss rail) or, more commonly, an external fitting t ...
instead of two separate scope rings.
On June 12, 2008, the M110 was ranked #2 on the U.S. Army's top ten inventions of 2007.
According to performance specification (MIL-PRF-32316 (AR) w/AMENDMENT 1, 5 October 2009):
3.4.1.1.1 Accuracy. The distance between the mean point of impact of each shot group, both unsuppressed and suppressed, shall be not greater than 1.1 inches at 300 feet.
3.4.1.1.2 Dispersion. The average mean radius (AMR) (see 6.11), of each shot group shall be not greater than to 0.68 inches at 300 feet. All targets shall be fired on using M118LR ammunition or equivalent, using five (5) round groups.
Sporting use
In 2009, the M110 rifle and commercial equivalents were added to the list of NRA-legal US service rifles under rule 3.1.6 of the NRA High Power Rifle Rules.
Replacement or reconfiguration of M110
In April 2011, according to
Military.com, the U.S. Army issued a request to the private sector to reconfigure or replace the current Knight Armament M110 sniper rifle, alleging that the current version of the M110 was not functioning well in the field and, according to industry officials and users in the field, required significant maintenance and replacement of parts.
The U.S. Army responded directly, claiming that the rifle was functioning perfectly, citing a 100% approval rating from the
173rd Airborne Brigade, and they were simply looking for a smaller, lighter version of M110 for the spotter in a sniper team.
The specifications the U.S. Army has issued are as follows:
# ''Operation:'' Semi-automatic
# ''Caliber:'' Compatible with 7.62×51mm NATO cartridges
# ''Accuracy:'' Capable of 1.3
minute of angle
A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...
dispersion or better with match ammunition
# ''Size:'' Overall length shall be reduced using a shorter barrel and/or collapsible buttstock. Maximum length not to exceed without suppressor. Desired minimum length is less than with stock collapsed.
# ''Weight:'' Weight shall be under 9.0 lb for unloaded rifle without optics and accessories
# ''Grip:'' A modular, adjustable pistol grip.
# ''Trigger:'' A non-adjustable match style trigger.
# ''Hand guard:'' A forend that includes a fixed 12 o’ clock rail with configurable 3, 6, and 9 o’ clock rails.
# ''Sound suppressor:'' A muzzle mounted, detachable sound suppressor.
# ''Muzzle device:'' A compensator/muzzle brake compatible with the sound suppressor.
# ''Bipod:'' Tool-less detachment featuring cant and pan/track capability.
# ''Day optic:'' An Army specified variable power day optic and compatible rings.
# ''Back up sights:'' Iron sights offset 45 deg from the DOS.
# ''Sling attachment:'' Flush cup, quick detach sling attachment points.
# ''Other:'' The upgraded M110 must meet the operational and environmental requirements that were fulfilled by the original M110 SASS.
M110A1 replacement
In July 2012, the U.S. Army requested sources to remanufacture the current M110 rifle into the Compact Semi-Automatic Sniper System (CSASS). The CSASS will be a shorter and lighter version of the M110 with a collapsible stock and removable flash suppressor, giving it an overall length of and a weight of unloaded. The Army wants a capability to convert 125 rifles per month, with the ability to increase to 325 per month.
The Army formally requested proposals for the CSASS in June 2014.
On 1 April 2016, the Army announced it had awarded
Heckler and Koch a contract with a maximum value of $44.5 million as winner of the competition to replace the KAC M110. The weapon selected was not specified, but was likely the
H&K G28; H&K is to produce 3,643 rifles.
A goal of the effort was to give snipers a weapon that didn't "stick out" as a sniper rifle; with a suppressor, the M110 is , longer than the
M4 carbine
The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO assault rifle developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively used by the US mi ...
and longer than the
M16A4 rifle. A minimum of 30 CSASS units will be used for production qualification testing and operational testing over 24 months.
H&K later confirmed that a modified G28 had indeed been selected as the CSASS rifle. The G28 is nearly 6 cm (2.5 in) shorter and 1.3 kg (3 lb) lighter than the M110 (unloaded and without a suppressor) and will cost about $12,000 per rifle.
The
U.S. Marine Corps was slated to begin receiving the CSASS in May 2018 to replace their M110 rifles.
However, as of 2022, all of the M110A1 units delivered were configured as squad designated marksman rifles (SDMR) rather than M110A1 CSASS rifles.
M110A2

The M110A2 is an improved version of the original M110 rifle with
M-LOK
M-LOK, for Modular Lock, is a firearm Rail Integration System, rail interface system developed and patented by Magpul Industries. The license is free-of-charge, but subject to an approval process.
M-LOK allows for direct accessory attachment ...
rails, an improved gas system, new suppressor, and adjustable stock.
This fills the gap of semi-automatic sniper rifles as most all of the M110A1 rifles issued were the SDMR variant and not designed for sniper work.
The M110A2 was first seen at
AUSA 2021 where it was displayed alongside a 14.5" SOCOM M110 rechambered for 6.5 Creedmoor.
The M110A2 was later seen at the 2022
Best Ranger Competition
The David E. Grange Jr. Best Ranger Competition is an annual competition held in Fort Benning, Georgia, hosted by the United States Army Infantry School, Airborne and Ranger Training Brigade. It is a two-person team competition where competitors ...
being used by a Ranger-qualified
101st Airborne Division
The 101st Airborne Division (Air Assault) ("Screaming Eagles") is a light infantry division (military), division of the United States Army that specializes in air assault military operation, operations. The 101st is designed to plan, coordinat ...
soldier.
The M110A2 is shorter than the original M110 and lighter as well at , which is comparable to the M110A1 SDMR's weight of with no attachments save an unloaded magazine. The decreased overall length does not come at the cost of barrel length as the M110A2 still has a barrel.
KAC had a 5 year $13 million contract in 2020 to supply the Army with M110 rifles and this was amended in 2022 to include the M110A2 version of the rifle.
The Navy and Marine Corps, which had previously been interested in the M110A1 CSASS, decided to instead pursue an M110 SASS PIP (Product Improvement Program) for FY2021 based on findings indicating improved range and lethality with the PIP compared to the M110A1 CSASS.
Funding for subsequent fiscal years has been devoted to this PIP.
M110A3 (6.5mm Creedmoor conversion)
The M110A3 is a
6.5mm Creedmoor conversion for SOCOM M110 rifles.
In October 2019,
NSWC Crane ordered KAC's self-termed M110K1 conversion kits to upgrade
USSOCOM's M110s to fire 6.5mm Creedmoor, with and barreled configurations.
These conversion kits included complete upper receiver assemblies chambered for 6.5 Creedmoor as well as new muzzle brakes, and B5 Systems collapsible precision buttstocks. New QD suppressors for 6.5 Creedmoor were to be ordered separately.
Users
*
*
*
* : Used by Army Special Forces
*
*
*
*
* : Used by
GSOF.
*
*
*
*
*
*
*
*
* : Used by
Polish Special Forces
The Special Troops Command () is the special forces Command (military formation), command of the Polish Armed Forces (SZ RP). The command was formed in 2007 and is the fourth military branch of the SZ RP.
Composition
The Special Troops Command (' ...
.
*
*
*
*
*
*
* : Reported to be used by special forces units under GUR, SBU, SSO and Ukrainian National Guard control.
Foreign soldiers in the International Legion have used them in combat missions.
* : Used by both
US Army
The United States Army (USA) is the primary land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of the United Stat ...
and Marine snipers.
See also
*
Tabuk Sniper Rifle
*
Chukavin sniper rifle
*
Dragunov sniper rifle
*
PSR-90
*
SR-25
*
Barrett M82
The Barrett M82 (standardized by the U.S. military as the M107) is a Recoil operation, recoil-operated, semi-automatic rifle, semi-automatic anti-materiel rifle developed by Barrett Firearms Manufacturing and produced in the United States.
Als ...
References
External links
M110 Semi-Automatic Sniper System (SASS) Fact sheetArchived
Knight's Armament Company product page on the SR-25 Series Rifles, includes the M110
Video demonstration of the M110 from Military Times
{{ArmaLite AR-10 derivatives
7.62×51mm NATO semi-automatic rifles
Sniper rifles of the United States
United States Marine Corps equipment
ArmaLite AR-10 derivatives
Designated marksman rifles
Military equipment introduced in the 2000s