The United States Army Squad Designated Marksman Rifle (SDM-R) is a heavily modified M16-series rifle intended to provide increased accuracy at longer ranges, giving infantry squads greater firepower. The SDM-R is designed to provide engagement capability at the squad level to 600 meters, similar to the needs expressed by members of USSOCOM that led to the development of weapons such as the Mk 12 Special Purpose Rifle (SPR) and the SEAL Recon Rifle. History The addition of an embedded marksman at the platoon or squad level has been a continuing process in the U.S. military. The U.S. Marine Corps (USMC) experimented with this during Project Metropolis, before creating the "Squad Advanced Marksman" (SAM) position along with the Squad Advanced Marksman Rifle (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 first and designated marksman second. The SDM is not meant to be a squad sniper 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 with 240 rifles provided for deployment in Iraq. The rifle was informally known as "the AMU rifle". The SAM-R was replaced from US Army service, mostly due to performance of match grade 5.56 NATO ammo in the DMR role. It was being replaced by the HK 417 as the army's new SDM rifle. Most were expected to be in service by 2020. Training The National Guard Marksmanship Training Center of the Arkansas Army National Guard 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, Texas. Many of the instructors are President's 100 recipients. Specifications The US Army used either M16A2 or A4 lower receivers previously supplied by either Colt or