Marine leaders have made the momentous recommendation to ditch the iconic M16 in favor of the M4 carbine as the new universal weapon for infantrymen.
The recommendation to swap the venerated rifle that has served as the grunt's primary implement of war since Vietnam now sits on the commandant's desk, pending his final review and a decision. But, the swap appears imminent and if approved will relegate the M16 to a support role. It follows a similar shift already underway in the Army.
With the endorsement of several major commands already supporting the switch — including Marine Corps Combat Development Command; Combat Development and Integration; Plans, Policies and Operations; Marine Corps Systems Command; and Installations and Logistics — final word is possible in weeks or months.
"The proposal to replace the M16A4 with the M4 within infantry battalions is currently under consideration at Headquarters Marine Corps," according to a jointly written response from the commands provided by Maj. Anton Semelroth, a Marine spokesman in Quantico, Virginia.
The change would be welcomed by infantrymen who say the M16A4 was too long and unwieldy for close-quarters battle in Iraq or vehicle-borne operations in Afghanistan. They tout the M4 for its weight savings, improved mobility and collapsible butt stock, allowing the rifle to be tailored for smaller Marines or those wearing body armor.
"I would have to say my gut reaction is it's the right choice and will do a lot of good for the guys in the infantry," said Sgt. Nathan West, an explosive ordnance technician with 8th Engineer Support Battalion, who carried an M4 on dismounted patrols and vehicle-borne operations during two deployments to Afghanistan as an anti-tank missileman.
"The M4 is a great weapons system that has done everything I have ever asked of it," he added.
The proposed switch also gets the thumbs up from senior marksmen such as the 1st Marine Division gunner, Chief Warrant Officer 5 Vince Kyzer.
"The carbine is a great weapon system for its time," he said. "...It will increase the war fighter's lethality and mobility."
Ultimately, if the move to the M4 is approved by Commandant Gen. Joseph Dunford, the M16 would be used exclusively by support personnel in communities like logistics or admin. Once approved, the swap could happen as fast as unit armories can issue weapons because the 17,000 M4s needed to outfit infantrymen who don't already use one are in the current inventory, said Barb Hamby, a Systems Command spokeswoman. Thus, officials described the move as an "improved capability for the infantry at no additional cost."
Wider adoption of the M4 is part of an overall small-arms modernization strategy that will look at incremental improvements, based on existing technologies as funding becomes available, according to a Marine official who said more details will likely be revealed in the months ahead.
For now, here is what Marines need to know about the infantry's next likely weapon of choice — the M4 carbine.
The call for a compact weapon
The M4 makes maneuvering in tight urban spaces easier with a 14.5-inch barrel and an overall length that is about 10 inches shorter than the M16A4, in a package that is a pound lighter at just over six.
No fight illustrated the need for a smaller primary weapon during ferocious close-quarters combat better than Operation Phantom Fury in November 2004, when Marines fought to wrest control of Fallujah from Iraqi insurgents, sometimes going hand-to-hand.
Rounding corners and getting on target in small rooms was difficult, leading to use of a tactic called "short-stocking," when a Marine places his rifle stock over his shoulder – instead of securely against the chest and cants his weapon45-degrees so he can still use his optics. It helps in maneuvering, but compromises recoil management and follow-up shots.
"We were taught to short stock around tight corners when we got to our platoon for deployment — it was something unofficial," said Ryan Innis, a former scout sniper with 2nd Reconnaissance Battalion, who left the service as a sergeant in 2013 after serving on the 22nd Marine Expeditionary Unit's anti-piracy raid force near East Africa.
Innis trained for shipboard operations — the closest of close-quarters combat — and said he was fortunate to be issued the M4 because the weapon's shorter length proved better for tight spaces.
"I would definitely agree the M4 is the way to go," he said.
The longer M16 was also challenging when hopping in and out of vehicles in full battle rattle, said West, who made his second deployment to Afghanistan in 2012 with 3rd Battalion, 9th Marines, as part of a vehicle-borne combined anti-armor team.
"Anytime you operate out of a vehicle, something compact makes life easier, especially when you need to get out quickly and engage [the] enemy," he said.
Even when he conducted dismounted patrols on his first Afghanistan deployment in 2011 with 1st Battalion, 6th Marines, the M4 he was issued helped in clearing compounds, jumping walls and crossing deep ditches, he said.
West never wanted to go back to the M16 because of the weight savings alone.
He said he started his first deployment carrying an M16A4; a Thor radio-controlled bomb jammer, a metal detector, and ammo for an M240 machine gun.
"There was even a time carrying an M32 grenade launcher, so you can see the amount of weight we were carrying at that time," he said. "Anything that takes weight off and keeps guys from getting tired so they are more aware of things around them is good. It is just a little less weight and just as effective of a weapon."
That is what the Marine Corps found when it began testing the ballistics of its infantry rifles and carbines using their improved M318 Mod 0 Special Operations Science and Technology round.
"The Marine Corps conducted an evaluation of its individual weapons (M4, M27 and M16A4), with specific focus on comparing accuracy, shift of impact and trajectory with improved ammunition, and determined the M4's overall performance compares favorably with that of the M27 IAR, the most accurate weapon in the squad," according to the written responses provided by Semelroth.
There are a few minor drawbacks to adopting the M4, but infantrymen seem to agree those are insignificant compared to the advantages.
Both Innis and West said trading in the M16's 20-inch barrel for the M4's 14.5-inch barrel does sacrifice some muzzle velocity, which translates into a slightly shorter effective range — although Colt markets both with an effective range of about 650 yards. But that isn't a significant concern given the closer ranges at which Marines and soldiers commonly engage enemy in modern warfare.
To strike the enemy beyond the range of the M4 or even the M16, each Marine fire team already has an M27 Infantry Automatic Rifle, which in semi-auto with its free-floating barrel and precision trigger also now doubles as the designated marksman's rifle. It's a role that will no longer be filled by the Squad Advanced Marksman Rifle, a match-grade M16 with a scope.
When the M27 can't get the job done, combined arms doctrine means indirect fire and air assets are just a radio call away, West said.
"As far as accuracy, there is not an effect," he added, saying a longer rifle only really matters when using iron sights.
Greater distance between a weapon's front and rear sights, known as sight radius, makes a weapon easier to aim. But that doesn't apply with the Rifle Combat Optic that the Marine Corps began using in 2005. The RCO is a type of reflex sight with which a Marine only needs to ensure the reticle is on target without regard for sight alignment.
When asked if the Marine Corps is making the right move, preeminent firearms expert Larry Vickers gave a resounding yes.
"I'm the first one to subscribe to this," Vickers said of the M4's increasing popularity as the preferred option for modern combat.
The M4's profile got a boost when the Army, which adopted the M4 in 1994 for special operations, began issuing it more broadly to deploying infantry.
Vickers, a retired master sergeant who served 15 years in the Army's 1st Special Forces Operational Detachment – Delta, commonly known as Delta Force, dismissed arguments against the carbine based on its shorter effective range, saying nearly all real-world infantry engagements happen inside 200 yards.
"Some argue beyond that the M4 carbine lacks effectiveness versus the M16, but the M16 is like driving a sports car with a six-cylinder engine," he said, because it is limited by the same small 5.56mm cartridge as the M4. "You can shoot 400 to 500 yards away, but you are still shooting a 5.56."
A longer barrel would make sense with a heavier hitting round like the .308, but unless Marines are given a larger caliber Vickers said the M4 is "bringing so much more to the table."
"It is the world's gold standard," he said.