Slugthrower 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 infantryman and a sniper (typically being deployed at ranges of 250–500 metres or 270–550 yards) 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 250 m or 270 yd or less, and up to 500 m or 550 yd, respectively) but do not require the extended range of a dedicated sniper rifle (typically employed for targets at ranges from 500–2,000 m or 550–2,190 yd).

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 rifles 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.