Though some of the rifle platforms originally entered service during the Cold War,
some have been updated and upgraded for the 21st century — and they're
part of the reason why the United States military is so lethal.
M4A1
The M4/M4A1 5.56mm Carbine is a lightweight, gas-operated, air-cooled, magazine-fed,
selective rate, shoulder-fired weapon with a collapsible stock.
It is now the standard issue firearm for most units in the U.S. military.
Equipped with a shorter barrel, collapsible stock, and detachable carrying handle (with
a built-in accessory rail) it provides soldiers operating in close quarters with improved handling
and the capability to rapidly and accurately engage targets at extended range, day or night.
A shortened variant of the M16A2 rifle, the M4 carbine provides the individual soldier
operating in close quarters the capability to engage targets at extended range with accurate,
lethal fire. The M4-series Carbine achieves over 80% commonality with the M16A2 Rifle
and replaces all M3 .45 caliber submachine guns, and selected M9 pistols and M16 rifles.
The Army is pursuing a two-phase PIP to keep the M4 carbine inventory strong. Phase I upgrades the
Army’s M4s to the Special Forces’ M4A1, while Phase II explores future improvements for the
M4A1 Carbine to deliver enhanced reliability, durability, ergonomics, and zero retention.
There are several benefits to upgrading M4s to M4A1s. Compared to the M4, the M4A1
has the full-auto capability, a consistent trigger pull, and a slightly heavier barrel.
The heavier barrel is more durable and has a greater capacity to maintain accuracy and zero
while withstanding the heat produced by high volumes of fire.
New and upgraded M4A1s will also receive ambidextrous fire control.
FN SCAR
The SCAR-L is a modern assault rifle of Belgian origin.
The SCAR-L was developed by Fabrique Nationale alongside the larger caliber
SCAR-H in response to a United States Special Operations Command requirement.
The FN SCAR is a gas-operated assault rifle and uses a short-stroke gas
piston to cycle the action. The design is modular and allows for different barrel lengths
and a variety of accessories. Some ergonomics, such as pistol grip and fire selector,
are similar to the AR-15. The monolithic upper receiver has
a long Picatinny accessory rail to mount one or more optical sights.
The SCAR-L fires the 5.56x45mm NATO round from a 30 round STANAG compatible detachable magazine.
It is a select-fire rifle with a rather low cyclic rate of fire of 625 rpm.
Effective range, depending on barrel length, ranges from 300m to over 400m.
An FN40GL 40mm low-velocity grenade launcher can be mounted under the forearm.
The SCAR-L was adopted by USSOCOM in 2009 as the Mk 16 Mod 0. The number of SCAR-L acquired was
limited since it offered limited value over the less cumbersome M4 already in service.
Instead larger numbers of SCAR-H were acquired. The SCAR-L has been adopted by several nations
as a standard-issue service rifle. Most notably by Belgium and Portugal. Various special forces
and law enforcement units around the globe acquired the SCAR-L in limited quantity.
M27 Infantry Automatic Rifle
An HK416D is a modified variant of a Heckler & Koch HK416 assault rifle. It was introduced in
2010. In turn, the HK416 is an improved version of the M4 carbine, that is widely used by the
US military. The HK416D has been adopted by the US Marine corps as the M27 in 2011.
Marines initially ordered 4,748 rifled and planned to obtain a total of 6,500 of these automatic
weapons. These partially replaced the M249 Squad Automatic Weapon, which was adopted back
in 1985. The main goal of adopting the M27 was to enhance automatic rifleman's maneuverability,
especially in urban terrain. However, the M249 will remain in service with the US Marine Corps.
The new weapon is distributed one per 4-men fireteam.
In terms of appearance and ergonomics, the M27 is very similar to the M16A4 and M4A1
and has a familiar feel for soldiers, reducing the time needed for retraining. However, the German
Heckler & Koch company successfully improved this weapon and cured a lot of its problems.
The M27 is a gas-operated automatic weapon. It is chambered for a standard NATO 5.56x45 mm
ammunition. It uses a patented gas piston system, derived from the Heckler & Koch G36 assault rifle.
This new operating system significantly reduced malfunctions and increased the life of parts,
compared with the M16A4 assault rifle. The new weapon is much more reliable.
The M27 has a 419 mm barrel. The barrel is cold hammer-forged and has a 20,000 round service life.
The charging handle is ambidextrous. Fire mode selector has three positions for "safe",
"semi-auto", and "full-auto".
This assault rifle is fed from 30-round magazines. At the start of testing this
automatic rifle used 100 round magazines, however, these were unreliable. It is compatible with all
standard NATO 5.56 mm magazines. However, the M27 was criticized for its low magazine capacity,
as it replaced the belt-fed 200 round suppressive fire weapon. Even though
the M27 is more reliable and more accurate, it loses in terms of firepower to the M249.
This magazine-fed rifle has to reload more often and is not able of sustaining fire.
The gunner of the M27 is expected to carry a total of 16 to 22 magazines, depending
on mission requirements. While the gunner of the M16A4 typically carries only 7 magazines.
The weapon has a telescopic buttstock, that can be extended or collapsed to suit the shooter.
The M27 has a Picatinny-type scope rail and can be used with various scopes. It comes
as standard with Trijicon 3.5x magnification day sight. There is a reflex sight on top for
close-quarters engagement. Also, there are flip-up diopter sight and front posts for emergency use.
The M27 has an effective range of 550 m against point targets and 800 m against area targets.
There are accessory rails on all four sides of the forearm. The M27 is compatible with
most current accessories for the M16 and M4, including a 40 mm under barrel
grenade launcher. Also, the M27 is often used with a detachable bipod and laser pointer.
M14
Though the M14's reputation suffered during the United States' involvement in Vietnam,
the rifle itself is quite rugged and offers good accuracy
and stopping power thanks to its larger 7.62 x 51 mm NATO cartridge.
Although the rifle was not well-suited to the wet jungle warfare of Vietnam — it was too heavy,
too long, and its wooden stock prone to warping — these two updates to the
platform have given the rifle a new lease on life.
Mk 14 Enhanced Battle Rifle
The Army and Special Operations Command redesigned the M14 from the ground up, giving the battle
rifle a new adjustable stock, pistol-style grip, collapsable bipod, as well as Picatinny accessory
rails and a modern optic, to give the old M14 better range as well as lightening the rifle.
M39 Enhanced Marksman Rifle
The Marine Corps had the same idea as the Army,
though they decided to modify the M14 a bit differently, resulting in the similar M39 EMR.
This modified rile also sported an adjustable stock and collapsable bipod
as well as an accessory rail that could mount optics.
It was, however, an interim measure and has since been mostly replaced
in Marine Corps service by newer, group-up designated marksman designs.