Designated marksman rifle A designated marksman rifle ( DMR ) is the weapon used by soldiers in the designated marksman ( DM ) role . The DM ' s role fills the gap between a regular infantry man and a sniper ( typically being deployed at ranges of ) and DMRs have been developed with this middle ground in mind . These rifles have to be effective , in terms of accuracy and terminal ballistics , at ranges exceeding those of ordinary assault rifles and battle rifles ( typically or less , and up to , respectively ) but do not require the extended range of a dedicated sniper rifle ( typically employed for targets at ranges from ) . DMRs , however , often share some basic characteristics with sniper rifles in difference to the weapons carried by others in the DMs unit . DMRs may have an attached telescopic sight , quickly deployed stabilizing bipod to allow optimized accuracy and low - recoil in temporarily fixed situations or an adjustable stock . They will , though , generally retain semi - automatic firing capability ( more rapid than bolt - action sniper rifles ) and a larger magazine capacity of 10 , 20 , or 30 rounds depending on the firearm in question . Designated marksman rifles compared to sniper rifles , battle rifles , and assault rifles . Most designated marksman rifles are based on an assault rifle that is currently issued by a nation ' s military , or on a battle rifle that was formerly issued . A battle rifle is a semi - automatic or full - automatic rifle that fires 7 . 62mm NATO or similar full - power rounds . Classic examples include the M14 , FN FAL , AR - 10 and Heckler & Koch G3 . These rifles were largely replaced by assault rifle s firing the 5 . 56mm NATO cartridge during the 1970s and 1980s . Some nations have also built rifles that were designed for the designated marksman from the ground up . Sights . All designated marksman rifles will have some type of optical sight with a higher magnification level than the standard issue rifle . For example , the SDM - R issued to the United States Army is fitted with a Trijicon 4x ACOG , while the standard - issue M4 carbine is equipped with an unmagnified Aimpoint CompM2 or CompM4 . Sometimes , the sighting system will be the only difference between the standard rifle and the designated marksman rifle , as is the case with the F88S DMR issued to the Australian Army . Sniper rifles often have even greater magnification than designated marksman rifles , for example , the M110 SASS used by the United States Army , is equipped with a Leupold 3 . 5 - 10x variable - power scope . However , some designated marksman rifles , such as the Mk 12 Special Purpose Rifle or the USMC Squad Advanced Marksman Rifle are fitted with scopes with similar magnification . Barrels . In some cases , the designated marksman rifle will have a longer barrel than the standard issued rifle . However , this is not universally true . In fact , the M16A4 rifle is still standard issue to the United States Marine Corps . The barrel on the Mk 12 Special Purpose Rifle , the current rifle used by the squad designated marksman in the USMC , is only 18 inches long - two inches shorter than the barrel on the standard rifle . Also , some rifles , such as the F88S Austeyr , have a barrel that is the same length as the standard service rifle . The FD - 200 has an accurised barrel , also found on designated marksman rifles . Most sniper rifles , such as the Accuracy International Arctic Warfare have a barrel with a length of 24 inches or greater . Only the SVD and similar designated marksman rifles have a barrel of this length . The designated marksman rifles based on the M14 have barrels 18 - 22 inches long . Ammunition . In most cases , a designated marksman rifle will share the ammunition used by standard issue rifles . In the U . S . military , designated marksman rifles chambered for 5 . 56mm NATO have available the 77 grain match - grade Mk 262 Mod 0 / 1 cartridge that enhances range to roughly 700 meters . DM rifles may be issued with standard ball ammunition , or special match - grade loads , such as 7 . 62mm NATO ' M118LR ' sniper round in the U . S . military . Action . All designated marksman rifles in use today use a semi - automatic action , with some also being able to fire in full - automatic mode . Some sniper rifles are semi - automatic , though the vast majority are bolt - action .