The Squad Designated Marksman Rifle (SDM-R) is an American

designated marksman rifle A designated marksman rifle (DMR) is a modern telescopic sight, scoped high-Accuracy and precision, precision rifle used by infantry in the designated marksman (DM) role. It generally fills the engagement effective range, range gap between a serv ...

used by 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 ...

. It is essentially a heavily modified

M16 rifle The M16 (officially Rifle, Caliber 5.56 mm, M16) is a family of assault rifles adapted from the ArmaLite AR-15 rifle for the United States Armed Forces, United States military. The original M16 was a 5.56×45mm NATO, 5.56×45mm automatic ...

designed to provide U.S. Army

designated marksmen A designated marksman (DM), squad advanced marksman (AD) or squad designated marksman (SDM) is a military marksman role in an infantry squad. The term ''sniper'' was used in Soviet doctrine although the soldiers using the Dragunov SVD were the ...

greater accuracy and firepower at longer ranges, increasing an

infantry Infantry, or infantryman are a type of soldier who specialize in ground combat, typically fighting dismounted. Historically the term was used to describe foot soldiers, i.e. those who march and fight on foot. In modern usage, the term broadl ...

squad In military terminology, a squad is among the smallest of Military organization, military organizations and is led by a non-commissioned officer. NATO and United States, U.S. doctrine define a squad as an organization "larger than a fireteam, ...

's effective range to up to 600 meters. The SDM-R is similar in development and role to the

SEAL Recon Rifle The SEAL Recon Rifle (nicknamed the "Sniper M4" and "Recce") is an American designated marksman rifle and assault rifle used by the United States Navy SEALs. Essentially a heavily modified M16 rifle, it is intended to provide SEAL snipers and de ...

and

Mk 12 Special Purpose Rifle The United States Navy Mk 12 MOD 0/1/H Special Purpose Rifle (SPR) is a designated marksman rifle that was in service with United States Special Operations Forces in the designated marksman role until 2017, also designed to be shorter than standa ...

(SPR), designed and produced for the

United States Navy SEALs The United States Navy Sea, Air, and Land (SEAL) Teams, commonly known as Navy SEALs, are the United States Navy's primary special operations force and a component of the United States Naval Special Warfare Command. Among the SEALs' main func ...

and the

United States Special Operations Command The United States Special Operations Command (USSOCOM or SOCOM) is the unified combatant command charged with overseeing the various special operations component commands of the Army, Marine Corps, Navy, and Air Force of the United States A ...

respectively. The SDM-R was replaced by the M110A1 SDMR, expected to enter service in the 2020s. In this role, the M110A1 retains the "Squad Designated Marksman Rifle" name.

History

The addition of an embedded

marksman A marksman is a person who is skilled in precision shooting. In modern military usage this typically refers to the use of projectile weapons such as an accurized telescopic sight, scoped long gun such as designated marksman rifle (or a sniper ri ...

at the

platoon A platoon is a Military organization, military unit typically composed of two to four squads, Section (military unit), sections, or patrols. Platoon organization varies depending on the country and the Military branch, branch, but a platoon can ...

level has historically been a continuing process in the

U.S. military The United States Armed Forces are the military forces of the United States. U.S. federal law names six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and the Coast Guard. Since 1949, all of the armed forces, except th ...

. 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 ...

(USMC) experimented with this during ''Project Metropolis'', before creating the "Squad Advanced Marksman" (SAM) role along with the

Squad Advanced Marksman Rifle The Squad Advanced Marksman Rifle (SAM-R) is a semi-automatic designated marksman rifle developed and used by the United States Marine Corps. It gave users the capability to provide fire in support of a rifle squad, providing precision fire in s ...

(SAM-R) specifically for this purpose. The 3rd Infantry Division followed suit in implementing a training program to have one marksman per squad, the Squad Designated Marksman (SDM), and developing a rifle, the Squad Designated Marksman Rifle (SDM-R). The SDM is an integral part of the squad and serves as a

rifleman A rifleman is an infantry soldier armed with a rifling, rifled long gun. Although the rifleman role had its origin with 16th century hand cannoneers and 17th century musketeers, the term originated in the 18th century with the introduction o ...

first and

designated marksman A designated marksman (DM), squad advanced marksman (AD) or squad designated marksman (SDM) is a military marksman role in an infantry squad. The term ''sniper'' was used in Soviet doctrine although the soldiers using the Dragunov SVD were the ...

second. The SDM is not meant to be a squad

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 ...

who engages the enemy with precision fire at long ranges, but instead is trained to directly support the squad with well-aimed shots at ranges slightly beyond the normal engagement distances for riflemen. Much like the U.S. Marine Corps SAM-R, the 3rd Infantry division SDM-R was an accurized M16 rifle built in-house by the

United States Army Marksmanship Unit The United States Army Marksmanship Unit (USAMU or AMU) is a part of U.S. Army providing small arms marksmanship training for soldiers and enhancing Army recruiting. The unit was originally established in 1956 at the direction of President of the ...

with 240 rifles provided for deployment in Iraq. The rifle was informally known as "the AMU rifle".

Replacement

The SAM-R has since been replaced in U.S. Army service, mostly due to the performance of match grade 5.56 NATO ammo in the DMR role. Its slated replacement was the

Heckler & Koch HK417 The Heckler & Koch HK417 is a battle rifle designed and manufactured by Heckler & Koch. Being the larger caliber version of the Heckler & Koch HK416, and chambered for the 7.62×51mm NATO rifle cartridge, it is intended for use where the penet ...

-based M110A1 SDMR, expected to enter service in the early 2020s.

Training

The National Guard Marksmanship Training Center of the

Arkansas Army National Guard The Arkansas Army National Guard (ARARNG) is a component of the Arkansas National Guard and the United States National Guard. National coordination of various state National Guard units are maintained through the National Guard Bureau. Arkansa ...

conducts the fourteen-day-long Squad Designated Marksman Course at Camp Joseph T. Robinson. Soldiers fire over 1500-rounds from the M16A4 rifle under the close supervision of course cadre. Another is done in Fort Benning, Georgia. Task Force Small Arms Readiness Group (TF SARG) conducts the week-long SDM course at the SARG academy at

Camp Bullis Camp Bullis Military Training Reservation is a U.S. Army training camp comprising in Bexar County, Texas, United States, just northwest of San Antonio. Camp Bullis provides base operations support and training support to Joint Base San Antoni ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

. Many of the instructors are President's 100 recipients.

Design

*The U.S. Army used either M16A2 or A4 lower receivers previously supplied by either Colt or

Fabrique Nationale de Herstal , trading as FN Herstal and often referred to as Fabrique Nationale, or simply FN, is a leading firearms manufacturer based in Herstal, Belgium, and former vehicle manufacturer. It was the largest exporter of military small arms in Europe . FN ...

. All rifles were equipped with a fixed A2

stock Stocks (also capital stock, or sometimes interchangeably, shares) consist of all the Share (finance), shares by which ownership of a corporation or company is divided. A single share of the stock means fractional ownership of the corporatio ...

and a

Knight's Armament Company Knight's Armament Company (KAC) is an American firearms and firearms parts manufacturer, known for producing the Rail Interface System (RIS) and the Rail Adapter System (RAS) grips for firearms use. The company produces a variety of firearms, ...

2-stage

match grade Match grade frequently refers to quality firearm parts and ammunition that are suitable for a competitive match. Sometimes it also refers to other devices and parts that are made with high precision in mind. Description In firearms, the term is ...

trigger The upper receivers were flat top style, but unlike the SAM-R and SPR, they did not have extended feed ramps. *Barrel: The 1:7 twist,

barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden stave (wood), staves and bound by wooden or metal hoops. The word vat is often used for large containers ...

from the M16A2 and A4 were replaced with a

stainless steel Stainless steel, also known as inox, corrosion-resistant steel (CRES), or rustless steel, is an iron-based alloy that contains chromium, making it resistant to rust and corrosion. Stainless steel's resistance to corrosion comes from its chromi ...

Douglas Barrels 1:8 twist, 20-inch barrel, with 12 flutes cut into the barrel to reduce weight. The front sight block was installed with 4 set screws instead of two taper pins. The SDM-R retained the A2-style

flash hider A flash suppressor, also known as a flash guard, flash eliminator, flash hider, or flash cone, is a device attached to the muzzle of a rifle that reduces its visible signature while firing by cooling or dispersing the burning gases that exit t ...

. *Sights and optics: The issued

optic Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

was a 4×32

Advanced Combat Optical Gunsight The Advanced Combat Optical Gunsight (ACOG) is a series of prismatic telescopic sights manufactured by Trijicon. The ACOG was originally designed to be used on the M16 rifle and M4 carbine, but Trijicon has also developed ACOG accessories for ...

(ACOG) (models TA31F, TA31RCO, TA01, TA01B, or TA01NSN). A Matech Industries 600-meter backup

iron sight Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescope ...

was also used. *Handguard: Daniel Defense DDM4 Rail 12.0 handguard, with an octagonal aluminum collar locking it to the upper receiver. The handguard provides a free-floating

Picatinny rail The 1913 rail (MIL-STD-1913 rail) is an American rail integration system designed by Richard Swan that provides a mounting platform for firearm accessories. It forms part of the NATO standard STANAG 2324 rail. It was originally used for mount ...

forend. *Bipod: A Harris S-L

bipod A bipod is a V-shaped portable attachment that helps support and steady a device, usually a weapon such as a long gun or a mortar. The term comes from the Latin prefix and Greek root , meaning "two" and "foot" respectively. Bipods are design ...

attached to an ARMS #32 throw-lever rail mount was mounted to the underside of the handguard. Since the handguard was free-floating, it did not come into contact with the barrel, and any pressure from the bipod on the handguard did not deflect the barrel.

Variants

The

82nd Airborne Division The 82nd Airborne Division is an Airborne forces, airborne infantry division (military), division of the United States Army specializing in Paratrooper, parachute assault operations into hostile areasSof, Eric"82nd Airborne Division" ''Spec Ops ...

examined an alternate version, based on 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 ...

. The barrel was to have been an long

fluted Fluting may refer to: *Fluting (architecture) *Fluting (firearms) *Fluting (geology) * Fluting (glacial) *Fluting (paper) *Playing a flute (musical instrument) Arts, entertainment, and media *Fluting on the Hump ''Fluting on the Hump'' is the ...

Douglas barrel with 1:8 twist. A mid-length gas system was to be used, along with the Daniel Defense M4Rail 9.0 handguard. This effort never went beyond the staffing process.

References

External links

Field Manual 3-22.9: Squad Designated Marksman training
{{ArmaLite AR-10 derivatives 5.56×45mm NATO semi-automatic rifles Designated marksman rifles Rifles of the United States ArmaLite AR-10 derivatives Military equipment introduced in the 2000s