Taking cover behind their tank escort, one man of this ranger patrol of the 5th RCT, U.S. 24th Infantry Division, uses his BAR to return the heavy Chinese Communist small arms and mortar fire which has them pinned down on the bank of the Han River.

GENERAL ARSOF HISTORY

Form Follows Function

A Brief Look at U.S. Army Standard Service Rifles and
Squad Automatic Weapons since WWII

By Troy J. Sacquety, PhD

From Veritas, Vol. 15, No. 1, 2019

ABSTRACT

The Army’s selection of a standardized caliber bullet has always determined the choice of its rifle and squad automatic weapon. Weight, rate of fire, lethality and bullet standardization are constant factors that guide the Army in adoption of new weapons systems.

TAKEAWAYS
  1. The bullet has always determined weapons design.
  2. The Army has consistently adopted more accurate, longer range, and lighter weapons. Yet, to deal with improved body armor, a new generation rifle will be heavier than the M-16/M4A1 while the M249 replacement will be lighter.
  3. Historically, the Army has benefitted from using squad level weapons systems that used the same ammunition.
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Since the beginning of modern warfare, the development of a cartridge that provided required maximum effective range and accuracy, penetration, and lethality, have dictated rifle and automatic weapons design. Form (rifle) follows function (cartridge desired). The development of a modern cartridge that was mutually compatible for a Squad Automatic Weapon (SAW), became the backbone of modern Infantry doctrine. A dependable SAW with a high rate of accurate long-range fire suppressed enemy concentrations and enabled the remainder of the rifle squad to maneuver. Ammunition compatibility with all infantry squad weapons was desired from a logistics standpoint because it meant one cartridge fits all. Ammunition redistribution during and after a firefight was simpler and more efficient.

The Army adopted its first modern infantry rifle in 1903, the M1903 Springfield, chambered in .30-06. The .30-06 Springfield cartridge reflected advances in ballistics and aerodynamics made by European militaries.1 At the time the .30-06 was adopted, ammunition weight was not a major factor because long range accuracy and lethality were the most important factors. The Springfield proved to be a reliable, accurate, and hard-hitting weapon in First World War trench warfare. However, as World War II loomed on the horizon, a bolt-action rifle with an internal five-bullet magazine was not sufficient to support infantry squad maneuver tactics based on the support capabilities of the M1918 Browning Automatic Weapon (BAR), the standard infantry squad automatic weapon.

Developed in 1917 and chambered in .30-06, the BAR proved devastating in the trench fighting of World War I. It was employed by the Army during World War II, the Korean War, and was used by indigenous forces in Vietnam. An exceptionally rugged and dependable weapon, the major shortcoming of the BAR was its weight (nearly 20lbs) and heavy twenty-cartridge magazine. The squad had to carry extra .30-06 ammunition for the BAR gunner, which reduced the individual rifleman’s basic load.

To increase firepower in the infantry squad, in 1936 the Army adopted the M-1 Garand rifle. Chambered in .30-06, it shared the same ammunition as the BAR. Considered one of the best rifles of WWII, it was unusual because it was semi-automatic with an internal eight- cartridge magazine.2 It gave an American infantry squad greater firepower than the Germans, Italians, or Japanese, who, through 1944, were primarily armed with bolt action rifles. Because of advances in firearms technology following the Korean War, the Army wanted a lighter standard service rifle with selective-fire.

As America moved deeper into the Cold War, it needed to adopt a new standardized cartridge. A full-sized .30-06 cartridge put too much strain on a redesigned rifle mechanism. In 1954 the Army adopted the smaller and lighter 7.62x51mm NATO cartridge. The bullet, with ballistic characteristics similar to the .30-06, was adopted as standard by the North Atlantic Treaty Organization (NATO). As opposed to the .30-06 of WWII, this new NATO cartridge allowed interoperability with allied forces.

To use the 7.62x51mm NATO cartridge, the Army first modified the M-1 chamber and barrel to fire the 7.62x51mm NATO cartridge and then designed the M-14 rifle in 1957 around that new standard cartridge. The M-14 replaced the M-1 as the standard service rifle and the BAR as the squad automatic weapon.3 While a reliable weapon, in practice the M-14 could not replace such a wide array of weaponry. The M-14 was a pound lighter and had a greater cartridge capacity (20) than the M-1, allowing soldiers to carry more cartridges and have greater firepower. The drawbacks were that its wood stock and length was not suited to the jungle environment of Vietnam, a conflict the U.S. Army became embroiled in after the adoption of the weapon. Although only used as the Army’s standard service rifle for a short time (1957-1967) before it was replaced by the M-16 family of rifles, the accurate M-14 remains in limited service for special roles.

The Army continued to use the 7.62x51mm NATO cartridge in the M-60 machine gun, conceived to take over the role of the M1919 medium machine gun.4 However, while it also displaced the BAR, the M-60 proved inadequate as a squad automatic weapon. It was so heavy that soldiers affectionately referred to it as ‘the pig.’5 It also fired different ammunition (7.62x51mm NATO) than the M-16 (5.56x45mm NATO), the rifle that replaced the M-14, requiring squad members to carry additional, heavy, non-compatible ammunition to ‘feed’ the M-60.

The AR-15 rifle, later adopted in modified form as the M-16, fully replaced the M-14 by 1969. The lighter selective-fire rifle fired a .223 Remington cartridge that evolved into the 5.56x45mm NATO cartridge in the 1980s. The cartridge was much lighter than the 7.62x51mm NATO cartridge, allowing each soldier to carry more ammunition. In addition, the recoil was less, reducing user fatigue and increasing the probability of second and third hits. The M-16, unlike the M-14, could also be fired controllably and accurately on automatic, an important consideration as the majority of the adversaries were armed with the selective-fire Soviet/Warsaw Pact/Chinese AK-47.6 The M-16, including its current variant, the M-4A1, has been the main U.S. Army service rifle for fifty years.

The move to the 5.56x45mm NATO cartridge also influenced the reintroduction of a purpose-built SAW. In an effort to increase rifle firepower, improve ammunition compatibility Army-wide, and provide a lighter automatic weapon for the squad, the Army adopted the M249 in 1984. Although its high rate of fire and lighter weight have served well, it needed to be modernized based on age and wear from decades of service. Furthermore, the M249’s size is not well-suited to room clearing in dense urban combat environments.7

Concerns about the lethality of the 5.56x45mm NATO cartridge against combat troops wearing body armor were voiced. According to Major Thomas P. Ehrhart, “the U.S. infantry weapon has devolved from the World War I rifle capable of conducting lethal fire out to 1,200 yards, to the current weapon that can hit a target out to 300 meters, but probably will not kill it [because of modern body armor] … the current U.S. infantrymen [is] less equipped to kill his enemy than his World War I predecessor.”8 Because of changes on the battlefield, the Army began research on replacing the 5.56x45mm NATO cartridge with one of greater lethality.9

To speed up the standard procurement process, U.S. Special Operations Command in 2016 investigated the commercial 6.5mm Creedmore cartridge as the basis for a more precise weapons system.10 While heavier than the 5.56, it had more lethality and accuracy than the 7.62x51mm NATO cartridge, today’s standard for sniper rifles. The 2017 operational tests showed that with rifles modified to fire 6.5mm Creedmore, soldiers “were twice as likely to hit their targets” compared to weapons with the 7.62x51mm NATO cartridge.11

That said, the Army is looking to replace the M4A1 and M249 with two new weapons and a government designed 6.8mm cartridge that “falls in the sweet spot … with all the good characteristics of the heavier 7.62mm but with more lethality and accuracy,” and weighing less.12 The new weapon ‘contenders’ must improve the rifle squad capabilities against emerging threats, according to Lieutenant Colonel Jason D. Bohannon, the Project Manager for the new weapons system. The internally developed 6.8mm cartridge, and the weapons built to fire it, will incorporate the latest technology, reduce bullet aerodynamic drag, and be more lethal. The improvements “should last for the next thirty years.”13 Because the firing mechanism will need to be more robust, the new rifle will be heavier than the current M4A1, but because of incorporation of new construction materials, the SAW will be lighter than the M249.

Thanks to the Joint Armament Facility for making these weapons available for photographing.

ENDNOTES

  1. “The M1 Garand Rifle,” see “The Springfield .30-06 Cartridge,” on internet at https://m1-garand-rifle.com/30-06/, accessed 4 June 2019. [return]
  2. National Park Service, “M1 “Garand,” U.S. Rifle caliber .30,” on internet at https://www.nps.gov/stri/upload/M1-Garand-Rifle-Manual_2018.pdf, accessed 4 June 2019. [return]
  3. Bruce F. Kay, “An Analysis of the Infantry’s Need for an Assault Submachine Gun,” (Master of Military Art and Science Thesis, U.S. Army Command and General Staff College, 1977), 8., on internet at https://apps.dtic.mil/dtic/tr/fulltext/u2/a044796.pdf, accessed 5 June 2019 [return]
  4. M 60 7.62mm Machine Gun, Global Security.org, on internet at https://www.globalsecurity.org/military/systems/ground/m60mg-history.htm, accessed 6 June 2019. The M-60 was originally conceived to take over the role of the M1919A6 Browning medium machine gun. [return]
  5. Chris Eger, “The M60 Machine Gun: It’s the ‘Pig Man’!,” Guns.com, 29 May 2013, on internet at https://www.guns.com/news/2013/05/29/the-m60-machine-gun-and-they-called-it-the-pig, accessed 26 June 2019. [return]
  6. Michael Shurkin, “A Brief History of the Assault Rifle,” The Atlantic, 30 June 2016, on internet at https://www.theatlantic.com/technology/archive/2016/06/a-brief-history-of-the-assault-rifle/489428/, accessed 12 June 2019. Robert Bruce, “M14 vs. M16 in Vietnam,” Small Arms Review, on internet at http://smallarmsreview.com/display.article.cfm?idarticles=2434, accessed 12 June 2019. [return]
  7. Jason D. Bohannon, interview by Dr. Troy J. Sacquety, 14 June 2019, USASOC History Office Classified Files, Fort Bragg, NC. [return]
  8. Thomas P. Ehrhart, “Increasing Small Arms Lethality in Afghanistan: Taking Back the Infantry Half-Kilometer,” (Fort Leavenworth, Kansas: School of Advanced Military Studies; U.S. Army Command and General Staff College, 2009), 24, on internet at https://apps.dtic.mil/dtic/tr/fulltext/u2/a512331.pdf, accessed 27 June 2019. [return]
  9. Todd South, “New rifle, bigger bullets: Inside the Army's plan to ditch the M4 and 5.56,” Army Times, 7 May 2017, on internet at https://www.armytimes.com/news/your-army/2017/05/07/new-rifle-bigger-bullets-inside-the-army-s-plan-to-ditch-the-m4-and-5-56/, accessed 12 June 2019. [return]
  10. Joseph Trevithick, “U.S. Special Operators Will Soon Be Using This 6.5mm "Assault" Machine Gun,” The Drive, 21 May 2019, on internet at https://www.thedrive.com/the-war-zone/28138/u-s-special-operators-will-soon-be-using-this-6-5mm-assault-machine-gun, accessed 13 June 2018. [return]
  11. Joseph Trevithick, “Special Operators Getting A New Round For Their Precision Rifles And An 'Assault' Machine Gun,” The Drive, 10 May 2018, on internet at https://www.thedrive.com/the-war-zone/20770/special-operators-getting-a-new-round-for-their-precision-rifles-and-an-assault-machine-gun, accessed 13 June 2018. [return]
  12. Todd South, “Army’s Next Squad Weapon Will Fire a Never-Before-Seen Ammo Combination,” Army Times, 7 May 2018, on internet at https://www.armytimes.com/news/your-army/2018/05/08/armys-next-squad-weapon-will-fire-a-never-before-seen-ammo-combination/, accessed 13 June 2019. [return]
  13. Bohannon interview. [return]