The Guns of Eugene Stoner
His firearm designs have influenced modern rifles and machine guns more than anyone else’s.
When you start talking about the greatest gun designers in history, there are four names that spring to almost everyone’s mind immediately: John Browning, Mikhail Kalashnikov, and Eugene Stoner. Samuel Colt is also frequently in that group, though his greatest firearm achievement wasn’t produced until after his death—but that’s a discussion for a different story.
Many of today’s semi-auto rifles are either directly based on, or use principals established in Stoner’s designs, including the iconic AR-15 and AR-10. The squad support machine guns of today, like the Knight’s Armament LAMG (made by a company Stoner co-founded) owe much of what they are to the design of the Stoner 63 and Stoner 86 machine guns. Not to mention the fact that Stoner also came up with the .223 Remington / 5.56 NATO cartridge design, which has been the U.S. military’s standard rifle round since the mid 1960s.
Elements of the AR-15 and AR-10—like their barrel extensions that allowed the receiver to be made of lightweight aluminum instead of heavy steel, the split upper and lower design of the receiver and their tool-less disassembly, and the rotating bolt carrier group—and Stoner’s willingness to adopt cutting edge materials like aluminum alloys and plastics changed the way gun builders thought about building guns forever.
Here’s a chronological tour through Stoner’s firearm design career, through all of its highs and lows.
Eugene Morrison Stoner was born on Nov. 22, 1922 in Gosport, Indiana to Lloyd Stoner and Billie Morrison. Upon graduating high school in Long Beach, California, he got his first job working at the Vega Aircraft Company installing armament.
During World War II he signed up for Aviation Ordnance in the U.S. Marine Corps and served int he South Pacific and northern China.
After the war, in late 1945, Stoner began working in the machine shop for an aircraft equipment company called Whittaker and eventually became the design engineer there.
Beginning at ArmaLite
Stoner got into Armalite through an acquaintance that was hired there as the head of engineering when it was still part of Fairchild Engine and Aircraft Corp working in the machine shop building prototypes. He became chief engineer in short order.
The AR-5 and AR-7 Survival Rifles
While working at the ArmaLite division in the early 1950s, Stoner developed a number of prototypes that never went into production, including the AR-3, AR-9, AR-11, and AR-12. He also designed the bolt action AR-5 survival rifle in .22 Hornet, which successfully filled a contract from the U.S. Air Force. The rifle was updated for the civilian market in 1959 as the semi-auto ArmaLite AR-7 Explorer in .22 LR.
Both the AR-5 and the AR-7 are designed so the rifle can be broken down into three parts with the barrel and receiver fitting inside the hollow buttstock, along with spare magazines, for storage. This made it easy to stow under a pilot’s seat and the .22 Hornet chambering provided enough power to hunt small game in a survival situation and for self defense, in a pinch.
The semi-auto AR-7 in .22 LR was produced and sold under license by several companies over the years on the civilian market after ArmaLite sold the rights, with varying degrees of quality and success. Notably the Charter Arms version was infamously unreliable, mostly due to lousy magazines and stocks that were prone to cracking.
In 1980, the design and productions rights went to Henry Repeating Arms and the rifle and magazines were revised, improving reliability and durability, including the replacement of the original plastic stock with a much tougher ABS material. The receiver also got a Weaver optics rail. It was renamed the Henry U.S. Survival AR-7 in 2018 and is still in production. It’s the company’s only semi-auto firearm.
The AR-10 Answers the Army’s Call for a .308 Rifle
In 1953, Stoner developed a prototype in his garage of the gas impingement system that would eventually be used in his AR-15 rifle.
In 1955, the U.S. Army began searching for a replacement for the venerable M1 Garand battle rifle. While it was a beloved and stout rifle, the Garand had shown several combat limitations during service in WWII and Korea, namely its relatively small capacity of eight rounds, lack of a detachable magazine, and the weight of the Garand, which tipped the scales at about 10 lbs.
The Army also wanted something that could fire in full auto and would be chambered for the newer .308 Win. cartridge, which offered similar ballistics to the Garand’s .30-06, but with smaller cartridges, less weight, and less recoil.
Stoner decided to solve the weight problem by incorporating aluminum alloys and advanced plastics from the aircraft industry into his gun’s design.
“My aircraft background experience allowed me to get into some of these lightweight materials, for instance, forged aluminum receivers which were rather unknown at the time in weapons, but there was nothing particularly new to what I’ve been doing all along on the aircraft equipment. And the fiberglass and all that,” Stoner said in a 1989 interview. “They were more or less materials that I’d been using all along but weren’t very well accepted or used in the gun business.”
“Though we managed to try it, we hadn’t changed the laws of physics very much. And so, therefore, the things that are really left to play with and to, you might say, improve on or change are the materials that come along,” Stoner said. “Every time there’s a new material, it may fit something or allow you to do something that you couldn’t do before because a material wasn’t available. Even finishes can make quite a difference, (along with new machining or fabrication techniques).”
At the Aberdeen Proving Ground, several guns went up against each other for the spot, including the T-44 and T-48 from Springfield Armory, and ArmaLite’s radical AR-10.
The AR-10 certainly stood out with its lightweight aluminum receiver and a stock and handguard made of plastic—very out-there ideas when guns were still firmly in the age of wood and steel.
The design feature that made all the difference was the use of a steel barrel extension to lock up the bolt rather than part of the receiver itself—this let Stoner use lighter and weaker aluminum alloys to create the upper and lower receiver, saving a bunch of weight. In the end, the first AR-10 weighed under 7 lbs., that’s three additional pounds of ammo and/or gear a soldier could carry for the same weight load as an M1 Garand.
The gun had a lot of other features going for it—it was highly resistant to dirt and sand thanks to its tight fitting ejection port cover, it could be reloaded rapidly, could launch grenades with blank ammo, and was easy to train troops to use thanks to its simple operation and disassembly.
The earliest AR-10s were even fitted with a belt feeding mechanism and you can see a man with an belted ammo carrier backpack hooked up to an early AR-10 blasting away in the ArmaLite promotional video below.
However, as is often the case in military gun trials, the most forward thinking and advanced design for the job did not win out, and the Springfield T-44 was chosen to become the M-14 rifle and was adopted as such in 1959.
From 1956 on, ArmaLite sold the AR-10 internationally through a licensing agreement, primarily via a manufacturer in the Netherlands, but sales of the weird new “plastic” gun were less than stellar.
Early Promotional Video from ArmaLite Featuring Eugene Stoner and the AR-10:
Today, AR-10 pattern rifles in .308 Win are made by a number of companies and you can build one from components just like you can an AR-15. Brownells also makes two reproductions of these early AR-10s from ArmaLite that were largely produced under license overseas, the BRN-10A and BRN-10B.
The BRN-10A is more like the earliest AR-10s with an open 3-prong Dutch-style flash hider, haevy fluting on the barrel beneath the handguard, and brown furniture meant to mimic the original fiberglass furniture. The BRN-10B has features present on later export rifles, including black furniture and a closed-prong, Portuguese-style flash hider.
The AR-15 and the .223 Remington
Despite the rejection of the AR-10, the advancements displayed in the AR-10’s design did not escape the attention of the military and the Army came calling for ArmaLite to work up a downsized version of the rifle to explore the long held military doctrine that a service rifle should be chambered in a large caliber for engagements at longer distances.
Modern battlefield experience was indicating that most engagements occurred at short-to-medium distances, meaning a smaller, high velocity, intermediate cartridge would be a better option in a service rifle. This would also allow a soldier to carry more rounds of ammunition and to, conceivable, fire it in full auto, allowing it to also serve the function of a submachine gun or squad support weapon if necessary.
The military wanted full-auto capability from the M14, and they got it, but the gun was uncontrollable firing 7.62 NATO in full auto and was limited by magazines with a 20-round capacity—some of the same limitations of the M1918 BAR designed by John M. Browning. Plus, it had other issues, like the fact that it was actually heavier than the M1 Garand at 10.7 lbs. loaded.
Stoner wasn’t only tasked with down-scaling the 7.62 NATO AR-10, but with inventing a new small-caliber, high velocity cartridge as well.
“I designed up a bullet and went over to Sierra Cartridge bullet company, close by in California and they said sure, we’ll build you one. So they took my prints and built up a bullet and we took it out, loaded it up and fired it in a conventional rifle and found out it would do just about everything they were asking for,” Stoner said of the advent of the .223 Remington.
“Then we went to Remington and Winchester and asked for quotes for loading this bullet up into commercial cases, and they (gave us quotes) but then they hesitated on delivering any, because what happened was, we were getting pressures up a little higher than they would have liked.
“So they came back with a cartridge with a slightly larger chamber size that alleviated getting the pressures up that high—they could put a little more propellant in, and different types, slower burning and get the velocities that I was asking for to get the penetration. They were looking for penetration on a steel helmet at 500 yards and also go through a 10 gauge steel plate at 500 yards.
“I said, ‘I have no objection going away from a standard cartridge case if that’s what you want to do.’ So they did and that became the .223 Remington as an identifier, so that it wouldn’t mixed up by somebody in the marketplace, though they had no intentions (at the time) of commercially (producing) it.”
But, at the time, the AR-15 was still just an exploratory project for the Army that didn’t ultimately lead to any gun sales for ArmaLite, as the Army’s recently adopted M14 was finally in production.
The AR Heads to Colt
At the end of the ’50s, ArmaLite’s parent company, Fairchild, was in a little financial trouble and they were pretty much done with the AR rifle project, which had been rejected by the military. The AR-10 was being produced in a few countries overseas, but the U.S. military was finally getting their M14s from Springfield and Fairchild saw the whole thing as going nowhere.
Before the end of the 1950s, ArmaLite licensed both the AR-10 and AR-15 designs to Colt with Robert Fremont from the AR-10 and AR-15 design team leaving ArmaLite to help Colt with developing the platform. Right around this time, ArmaLite launched the previously mentioned AR-7 Survival Rifle, a .22 LR version of its successful AR-5 military survival rifle, aimed at the civilian market.
“Colt Industries acquired the proprietary rights for the AR15 rifle from Fairchild Aircraft Corporation in January 1959 at a cost of $75,000 plus a 4 percent royalty on all weapons produced,” says firearms historian T. Logan Metesh of High Caliber History. “An additional $250,000 and 1.5% royalty on each rifle was paid to Mr. Robert W. MacDonald, president of Cooper-MacDonald, Inc., the firm that brokered the deal, as a finders fee.”
The royalties are even more lucrative than they seem as they were tied to the gas system used in the AR-10 and AR-15 specifically, according to Ian McCollum of Forgotten Weapons.
Stoner also left ArmaLite for Colt in 1961, but before he did, he began working on the AR-16, which never left the prototype stage. It morphed into the AR-18, which was later produced and was a good seller for ArmaLite and later for Colt. It was a simpler stamped metal design with a side charging handle and no buffer tube, allowing for a folding stock.
The AR-15 Becomes the M16
At the dawn of the 1960s, the U.S. Air Force, now its own branch separate branch from the army, was using the WWII-era M2 Carbine to outfit its armed security troops guarding air bases and missile installations. At the same time, the M2 carbine was one of the guns the Army had decided would be replaced by the M14 and it was taken out of circulation, meaning there were no longer reliable stockpiles of spare parts for the Air Force to pull from.
Fortuitously, in 1960, Gen. Curtis LeMay was given a demonstration of the Colt Model 601 (with green furniture), the company’s first iteration of the AR-15, at a birthday party, according to McCollum (some say it was at a July 4 party). It was this little range session with watermelons as targets that got the ball rolling for this obscure rifle to become the longest serving standard service rifle in the U.S. military.
In 1961, LeMay was promoted to Chief of Staff of the USAF and requested 80,000 AR-15s to replace the M2 carbines in use by USAF security personnel, but the request was rejected because the brass didn’t want two calibers in the supply chain, and the M14 project was still on in full force. We’ll just ignore the fact that the M2 carbine was chambered in .30 Carbine and the M14 was chambered in 7.62 NATO.
However, in October of that year, William Godel of the Advanced Research Projects Agency (ARPA) realized the U.S. was only able to send relics of the world wars as aid to allies in Southeast Asia, which were determined to be inadequate. He sent 10 AR-15s to South Vietnam for testing by indigenous soldiers under U.S. advisors. In 1962, as part of Project Agile, he sent another 1,000 after receiving enthusiastic responses from the field. From this testing, ARPA drafted a report recommending the AR-15 as the U.S. military’s service weapon.
This generated a bit of a pissing contest with the Army, as the Green Machine insisted the M14 was the right choice, and conducted its own test to prove it, which was later determined to be biased.
It all came to a head in 1963. The Special Infantry Weapon (SPIW) program was scheduled to deliver a new infantry weapon by 1965 and M14 production was completely terminated. But Secretary of Defense Robert McNamara learned there weren’t enough M14s in the pipeline to outfit all of the military, and a stop-gap measure was needed, at least until ’65, especially with the situation in Vietnam heating up more and more every month.
The AR-15 was the only infantry weapon that had gone through enough testing at that point and could be issued to all branches of the service.
In November, McNamara approved an order of 85,000 rifles from Colt for the Army and Marine Corps. Another 19,000 M16s were ordered for the Air Force to appease Gen. LeMay. The SPIW program evaporated without achieving its goal and by the end of the decade, the M16 was the military’s new service rifle.
The M16, the XME16E1, and the Forward Assist
One important thing to note about M16s from this era—the Air Force technically got M16s while the Army got the XM16E1. While the Air Force was cool with the gun after the furniture was made black and the shape of the charging handle was changed, the Army didn’t like the fact that there was no way to manually force the bolt closed on the gun. The charging handle could only retract the BCG, but not push it forward. This was a major sticking point that prompted Colt to add a “forward assist” to the Army’s XM16E1 rifles.
The device allows the user to force the bolt into battery via teeth cut into the bolt carrier if it gets hung up cycling a round, and its merits have been debated ever since. The Air Force and the Marines, which had both tested the rifle, and Stoner himself objected to the addition. The Air Force noted, “During three years of testing and operation of the AR-15 rifle under all types of conditions the Air Force has no record of malfunctions that could have been corrected by a manual bolt closing device,” adding that the forward assist would add weight and complexity, possibly reducing reliability.
Stoner said he was of the opinion that if a round fails to chamber in a rifle, it’s far better to remove the round and see what the problem is than to force it into the chamber and fire it. And, in fact, the bolt carrier of an AR has an indent that faces the ejection port, which Stoner put there so a person can use their thumb to push the bolt closed if it were, say, released slowly to avoid noise.
Col. Howard Yount, who managed the Army procurement, would later say the forward assist was added on direction from senior leadership and not because of any complaints or test results. “The M-1, the M-14, and the carbine had always had something for the soldier to push on; that maybe this would be a comforting feeling to him, or something,” he said in testimony.
However, the chrome-lined chamber that McNamara himself had said was a needed improvement was not added to the rifle. This would come back to haunt him.
By 1965, over 300,000 rifles had been purchased from Colt. They came with 20-round magazines, which were found to be more reliable than 25-round mags developed by Colt. Soldiers would not begin receiving 30-round mags until the end of the war, and even then troops typically loaded 28 or 27 rounds so they would feed better.
Colt would hold the contract for M16s and their variants for the military until 1988 when production was taken over by FN Herstal.
One simply cannot talk about the introduction of the M16 without talking about the horrid reputation it gained among those asked to go into battle with the earliest rifles that were issued en masse.
The Army began issuing the XM16E1 in March, 1965 and terrible stories began to come back about the bodies of soldiers being found after firefights next to jammed M16 rifles in the jungles of Southeast Asia. Word quickly spread that the Army’s new “plastic guns” were jam machines that were getting men killed.
These malfunctions were not the result of poor design, but rather of the quagmire that is military bureaucracy coupled with stupidity and ignorance.
One of the first big issues was that, for some ungodly reason, the Army got it in its big green head that the M16 was a “self-cleaning rifle” or, at least, that it did not require cleaning at all.
How this notion got started is anyone’s guess, but the idea was so persistent that the Army’s M16s were issued without a cleaning kit and troops were told no cleaning was necessary. Additionally, the rifle, which was vastly different from the M-14s and M1 Garands the soldiers had trained with, didn’t come with a manual of any kind.
Stoner gave a chronology of the various mistakes made by the military during the introduction of the M16 from his perspective in a 1989 interview when discussing the first batch of M16s bought by the Army.
“The Army didn’t furnish any training manuals. They didn’t even have a bore brush or a cleaning rod with these weapons,” Stoner says. “And they issued 85,000 of them.”
But lack of proper training and support gear for the M16 was only part of the problem. The rest was caused by the Army’s choice of 5.56 ammo for the rifles.
“A very sad thing that happened was that the Army then took over the task of coming up with a tech data package for the ammunition,” Stoner says in the interview. “They specified rather loosely what they really wanted and that turned out to be a very bad situation because they specified, for instance, muzzle velocity and chamber pressure, and nothing else. Which meant that the gas port pressure—or the pressures tapped off to operate the mechanism—wasn’t even specified in the tech data package.”
“So the Army then allowed this to happen, and the ammunition that started coming down the supply line to meet the Army requirements was really loaded with a different propellant than what we ever used in the weapons before that, namely it was a ball propellant rather than the IMR propellant,” Stoner says.
The M16 and its 5.56 ammo had been tested and approved using DuPont IMR8208M extruded powder—but when DuPont told the military they couldn’t produce enough propellant for them, it was switched to Olin Mathieson WC846 ball powder, which burned much dirtier, creating more fouling. These effects were enhanced by the rifle’s direct impingement gas system, which naturally lets more fouling into the action and chamber.
With all the extra fouling and no way to clean the rifles, soldiers began to have failure-to-extract jams, which means the fired case remains in the chamber—this is the most difficult kind of jam to clear, usually requiring a cleaning rod to force the stuck case out from the muzzle end.
Additionally, the fouling problem was made worse by the fact that these M16s lacked a chrome-lined chamber, as previously mentioned, further promoting fouling and corrosion, especially in the humid jungle climate, and contributing to the failed extractions. This may also have been exacerbated by soldiers and Marines using the forward assist to force cartridges into heavily fouled chambers, from which the extractor could not free them.
But that’s not all the different propellant did, according to Stoner.
“In this case, the weapon was designed and the gas port was established to operate at a certain gas port pressure to operate the mechanism. And by going to the ball propellant, the first thing that happened, it increased the pressure considerably, therefore it ran the firing rate of the weapon up,” Stoner says. “I mean, not just a little bit, but quite a bit. In other words, into the neighborhood of 200 to 300 rounds per minute more.”
That alone caused jams, as the bolt was simply cycling too quickly. Stoner said in the interview that the problems with the new propellant, the increased fouling, and the lack of proper training and equipment could each have probably been quickly dealt with on their own, but not combined.
“These troops started going overseas (to Vietnam), who had been trained with another rifle, and suddenly, they were given this new rifle with no equipment, no training manuals or anything, just said, ‘Go get ‘em, fellas,’” Stoner said. “At the same time, they got this propellant that was making the weapon malfunction—firing too fast and doing a lot of other things.
“This rifle had never been tested with that type of propellant. All the millions and millions of rounds we fired had all been done with an IMR propellant as the known and then suddenly, without any…field tests of any magnitude, they introduced this thing into a wartime situation.
“Either the lack of training or the propellant change could have probably been tolerated, but not all together. In other words, when you put the lack of training, lack of maintenance equipment, and the new propellant, and pour them into the same situation all at one time—that’s what caused the big problem.”
“It became really almost a disaster because they had weapons completely failing in firefights. It just became a real mess and it became the target of a congressional investigation.”
Road to the M16A1
This mess prompted incremental changes made to the rifle and ammo—plus the issuing of rifle maintenance equipment.
In 1967, the XM16E1 was adopted as the M16A1, solving most of the problems with the rifle. It was also issued with a new cleaning kit, powder solvent, and lubricant.
In place of the M16’s three-pronged flash hider, which had a tendency to get caught on gear and foliage, the A1 featured a “bird-cage” flash hider.
It came with a cleaning kit that could be stored in the rifle’s buttstock, as well as a comic-book style manual explaining how the gun worked and how to maintain it. The barrels initially had chrome-plated chambers to help slow the build-up of fouling and later, fully lined bores were introduced.
The receiver also included a rib on the side to help prevent accidental activation of the magazine release, especially while closing the ejection port cover. This is called fencing.
Another small but significant change was that the hole in the bolt that accepts the cam pin was crimped inward on one side in such a way that the cam pin cannot be inserted with the bolt installed backward. If the bolt was installed backward on previous models, it would cause failure-to-eject malfunctions.
All of these changes, as well as an emphasis on regular, religious cleaning of the M16A1, resulted in malfunction reports steadily decreasing to acceptable levels.
The full-length triangular handguard remained until the introduction of the M16A2, which had a round, ribbed handguard.
In 1969, the M16A1 officially replaced the M14 as the U.S. military’s standard service rifle. In 1970, the new WC 844 powder was introduced to reduce fouling.
The M16A2, M16A3, and M16A4 were later introduced over the years to adapt the rifle to modern optics and accessories.
The M4 Carbine
During the Vietnam War, some soldiers were issued a carbine version of the M16 called the XM177, made by Colt, with a 10-inch barrel and a telescoping stock, making the gun much more compact. It also had a “flash hider/sound moderator” on the muzzle, to reduce muzzle flash and report.
The later XM177E1 included the forward assist that was added to the M16A1.
The XM177E2 had a slightly longer barrel of 11.5 inches to accommodate the attachment of Colt’s XM148 40mm grenade launcher, the predecessor to the M203.
The latter gun is often referred to as the Colt Commando and was marketed as the CAR-15.
These carbines were issued to special forces, helicopter crews, Air Force pilots, officers, radio operators, artillerymen, and other non-front-line riflemen. Colt later returned to the Commando design with the Model 733, which is basically an XM177E2 with the features included on the M16A2.
In 1984, trials began for the XM4, or the Colt Model 720, with a barrel length of 14.5 inches. The carbine was adopted as the M4 in 1991 as an official replacement for the WWII-era M3 “Grease Gun.” In 1994, it replaced the M9 pistol and the M16A2 for some troops.
The M4 became the preferred firearm during the wars in Iraq and Afghanistan, with troops preferring the compact firearm over the long M16s for use in largely urban environments with lots of potential for close-quarters combat.
The original M4 had a 3-round burst selection while the M4A1 and subsequent models have a full-auto firing mode instead.
The Colt Years and the Stoner 63
After Stoner went to Colt, in addition to tweaking the AR-15, he went to work designing the remarkable modular Stoner 63 Weapon System.
This is one of the coolest military guns ever made, though it wasn’t issued in any significant numbers. It was a 5.56 modular system that could be configured as a rifle, a carbine, a top-fed light machine gun (Stoner called this the Automatic Rifle configuration), a belt-fed squad automatic weapon, or a vehicle-mounted weapon.
The Stoner 63 and its various configurations were built around a common receiver with interchangeable parts.
It was primarily built by Cadillac Gage, not Colt, and saw limited combat use by U.S. special forces personnel during the Vietnam War. As explained in the video below from Forgotten Weapons, the Stoner 63 worked very well, when it was maintained well. The reason it isn’t better known is mostly a question of timing.
How the Stoner 63 Worked
The Stoner 63 is a piston-driven, air cooled firearm that fired from a closed bolt in its rifle and carbine configurations and from an open bolt to help shed heat in machine gun mode.
Much like the AR-15, the 63 has a rotary bolt with 7 locking lugs that engage a series of recession in the barrel extension. It is actuated by a conventional long-stroke piston.
The buffering system in the bolt carrier is unique in that it contains a steel shim in front of the carrier cap and a set of 27 saucer-shaped Belleville washers oriented in opposing sets of three. These washers absorb energy from the piston stroke by deforming into a flat plate and then returning to their original shape, propelling the reciprocating parts forward. These replaceable plates had a lifespan of about 40,000 to 50,000 rounds.
When the gun was being used as a machine gun, belted ammunition was moved by a roller riding in the channeled feed arm that is actuated by the reciprocating movement of the bolt. It could be configured to feed from the right or left side.
The 5.56 belted ammo was held by disintegrating metallic links, which were scaled-down versions of the M14 link developed for the M60 machine gun chambered in 7.62 NATO.
The ammo belt was originally contained in a 150-round plastic ribbed container with a tab allowing it to be clipped to the left side of the feed tray. Early ammo boxes were olive drab and were later changed to a black plastic container. The boxes for the later 63A had a 100-round capacity to improve balance. These boxes could be attached on the left side of the receiver or held in a bottom box carrier when using the right-hand feed mechanism.
There were also several drum-style belt carriers designed for the left-hand feed system, with a 150-round drum being the most popular with the Navy SEALs in Vietnam. A 250-round drum carrier was developed, but it added too much weight. Some SEALs also used converted RPD belt carriers for their 63s.
When used as a rifle, carbine, or Automatic Rifle, the 63 used 30-round steel box magazines. Later, to save weight, aluminum box mags were developed that cut the weight of unloaded mags in half to 4 oz. Mags with a 20-round capacity were also made.
One of the features that made the Stoner 63 extremely attractive and versatile was its interchangeable barrels that could we swapped in seconds without tools. The system has 5 barrel options: the rifle, carbine, automatic rifle, and two machine gun barrels: a heavy barrel and a shorter “Commando” length.
The standard MG and AR barrels were 20 inches while the Commando barrel was 15.7 inches and fluted to reduce weight and enhance cooling, but because the gas port was so close to the muzzle, there were sometimes cycling issues, though this was the configuration preferred by most Navy SEALs who used the weapon during the Vietnam War.
The MG barrels also include a manually adjustable gas regulator with three settings, including a “fouled” setting that opens up the gas system the most.
The barrels all had the quick-detach capability. To remove a barrel on a 63, one simply pushed down on a latch on top of the gun in front of the feed cover (or magwell) while pulling the barrel forward.
Interestingly, the first working prototype of the 63 was introduced in 1962 and was chambered in 7.62 NATO. It was called the M69W, so that the name would read the same upside down—a nod to the gun’s unique fully invertible receiver.
The next design was the Stoner 62, which was still chambered in 7.62 and was not a prototype—it was intended for mass production, but those plans were shifted when the U.S. military moved toward the 5.56 NATO as it adopted Stoner’s AR-15 as the M16.
The first 234 Stoner 63s in 5.56 NATO were produced in February, 1963 at the Cadillac Gage Costa Mesa, California facility. In the fall of 1964, production was moved to the company’s plant in Warren, Michigan. With the move, the grip and stock of the gun were switched from wood to polycarbonate plastic.
In March, 1963, the DOD’s Advanced Research Projects Agency showed interest in the Stoner 63, ordering 25 of them in various configurations that would later be sent to the Marine Corps Landing Force Development Center in Quantico for evaluation.
The Marines liked the Stoner 63 as a rifle and as a machine gun because of its light weight and high ammo capacity.
A number of issues cropped up during subsequent Army testing, often because the ammo requirements were kind of bonkers. The Army wanted the gun to perform across a very wide pressure range. The tracer ammo used in the trials was so underpowered that it couldn’t even cycle an M16. This effected the Stoner 63’s perceived reliability and it was deemed “unacceptable for service use.”
Per the Army’s recommendations, the updated Stoner 63A included a stainless steel gas cylinder, a two-position fire selector with a separate manual safety, and tweaks to the ejection port cover and belt feed mechanism.
At the end of the 1960s, based on the USMC interest, Cadillac Gage began a program to upgrade the Stoner 63′s light machine gun configuration. Several changes were made and it was designated as the XM207 Light Machine Gun. A tweak in this design solved the bulk of misfire issues with the platform—a stack of Belleville spring washers absorbed some of the shock and bounce when the firing pin struck the primer. By changing the configuration of the washers, a higher spring rate was achieved, preventing most of the misfires.
When the 63 was cold, it had a firing rate of about 650 rounds per minute. But when the gun heated up after firing several hundred rounds, the cycle rate could climb as high as 1100 rpm, which, of course, caused a number of malfunctions.
A “rate regulator,” similar to the one used in the M60 machine gun, was added in the buttstock of the XM207. It was basically a shock absorber that eliminated the recoil bounce off the back plate, allowing the main drive spring to control the forward velocity of the carrier. This addition capped the gun’s cyclic rate at about 800 rpm, resolving the mechanical issues seen at higher rates of fire.
The belt feed system was also improved, enhancing reliability. An expandable sealing ring in the gas chamber was added to minimize external gas leaks and keep chamber pressure up so even low pressure tracer rounds could be fired without issue.
In addition to all this, the gun was also expected to be able to fire a muzzle-mounted anti-tank grenade, which exerted about 5,000 lbs. of force on the gun’s stock—a battering the polycarbonate material simply couldn’t hold up to. To strengthen the design, the buttstock was pressure filled with a lightweight urethane foam adding structural rigidity and high impact strength.
The XM207, including all the design changes, passed all the Army’s tests—right about the time President Richard Nixon announced the U.S. would begin withdrawing from Vietnam. This brought any further development or deployment of the improved XM207 screeching to a halt.
The Stoner 63A in Vietnam
Despite all that, the Stoner 63A did see combat in Vietnam as a small number of the guns were given to the newly established U.S. Navy SEALs in Southeast Asia. Plus, in 1967, the Stoner 63A was tested by Lima Company, 3rd Battalion, 1st Marine Reg., 1st Marine Div. where riflemen were issued the rifle configuration, while officers and other personnel got the carbine variant. The Automatic Rifle configuration was deployed as a squad automatic weapon and Lima’s weapons platoon got the light machine gun and mounted machine gun configurations.
In 1970, after the Army had approved the XM207 variant, it was issued to select Army Special Forces for evaluation. They concluded that the gun was simply too complex and required too much maintenance to be widely issued.
For special forces troops who had a chance to prepare their gear before a relatively short mission and then to maintain the gun afterward, it was great and worked well—but for an often quickly-trained grunt humping search-and-destroy missions for weeks at a time in the jungle, there were too many ways the gun could pick up dirt and crud, and too many parts that could be broken or lost in the bush, rendering it useless.
“The feed pull, that was the one part that consistently broke. And if there was no time to replace it, you brought home a 13-pound club,” says former SEAL Lt. Cmd. Michael J. Walsh in the video above. “It was maintenance intensive, which was an undesirable feature of it. You had to baby it.”
The book The Element of Surprise: Navy Seals in Vietnam, is, at times, a love letter to the Stoner 63. It was the weapon the author, Darryl Young, carried most often during his first tour as a SEAL operating in the Mekong Delta, specifically in a place called Dung Island. He often praises the Stoner’s ability to lay down an immense amount of suppressive fire and allow a small platoon to quickly gain fire superiority over a larger force of Viet Cong and NVA troops. But he does mention, many times, that the absolute first thing the SEALs did when returning from a mission was break down and thoroughly clean the Stoners and all their weapons—usually even before they removed their wet, muddy clothes and camo facepaint.
For SEALs in Vietnam, the ammo capacity and the ability to carry it in belts of any length far outweighed any drawbacks. Their missions were generally quick, only including one evolution of darkness if things went well, but they were usually conducted deep in enemy territory with no resupply possible if things went wrong and the only hope of escape being a speedy extraction by boat or helicopter. As such, each SEAL with a Stoner 63 carried about 500 rounds of ammo on them. Regardless of their weapon, they usually didn’t carry food and took maybe a canteen of water along.
Young says in his book that he had a custom nylon vest made that held five 100-round magazines for his Stoner, and often mentions how having a fully loaded ammo can in the machine gun made him feel more secure. On one mission, he writes that he fired so many rounds while heading to an extraction site with the enemy on their tail that he loaded his last magazine before getting on the boat.
The 63 not only let the SEALs carry the payload they needed, but also provided an intense amount of firepower on demand, which was important for their small platoons of 14 men, with seven per squad. Plus, the 5.56 chambering made it very controllable in full auto, firing from the hip or the shoulder.
“It greatly increased our firepower,” says Walsh. “If you had six Stoners and and four M60s in a 14-man SEAL platoon, you’ve got company-sized firepower, just with machine guns alone. You could lay down a tremendous base of firepower and you could protect the insertion craft on the way back…and that got you home.”
During the war, Cadillac Gage engineers worked with the SEALs directly and they could send their problems and concerns directly to them in Michigan, where they made changes fairly quickly.
Walsh recounts one particular incident spurred CG to make a small, but important change. The pin at the rear of the receiver that holds the two halves of the receiver together had a tendency to vibrate out of the gun. A SEAL was riding in a boat with his 63 between his legs, stock on the deck and the muzzle near his chest. The pin vibrated completely out of the gun, allowing the receiver halves to separate enough to release the sear. The SEAL took several rounds in the chest and was killed. The engineers quickly added a locking double screw to replace the so-called “dead-man pin.”
The military generally turned its back on the gun in 1971 and Cadillac Gage ceased production with about 4,000 63 and 63A units produced. The SEALs, however, continued to use the Stoner 63A as the Mark 23 Mod 0 machine gun through the Vietnam War and into the late 1980s when it was phased out in favor of the M249 SAW.
These days, the Stoner 63 is getting a bit of a new life, though a limited one, via the M96 Expeditionary rifle made by Robinson Armament Company, which is mostly based on the 63.
Robinson originally made the M96 between 1999 and 2005 in carbine, rifle, and top fed configurations. At SHOW Show 2020, Robinson announced it would be creating another run of the M96 from parts it had in stock, though production has been delayed waiting for the manufacture of several parts that were lacking.
They had a model of the Automatic Rifle configuration at their booth on the show floor and were demonstrating the quick barrel change feature, carried over from the Stoner 63, seen below.
Continued Machine Gun Work
In 1971, Stoner co-founded Ares Inc. in Ohio where he continued with the Stoner 63 concept in the form of the Ares Light Machine Gun, also known as the Stoner 86. While at the company, he also designed the Future Assault Rifle Concept (FARC).
Stoner left Ares in 1989 and joined Knight’s Armament Company in 1990 where he continued to work on the machine gun design as the Stoner 96.
These days, Ares Inc. produces fire control systems, turret systems, small arms, automatic cannons, and industrial machinery.
You can see a lot of Stoner’s work and design elements from the 63, 86, and 96 in the Knight’s Armament Assault Machine Gun, which you can get a look at here.
The SR-25 Rifle
While at KA, Stoner endeavored to pick up where he left off with the AR-10, and it was a solid success in the form of the Stoner Rifle-25 (SR-25) in 7.62 NATO, which saw military service as the Navy’s Mark 11 Mod 0 Sniper Weapon System.
The SR-25’s name comes from adding together the numerical portion of the AR-10 and AR-15 names.
The rifle was released in the early 1990s and featured an improved AR-10 design with M16A2 advancements and common parts.
The original rifle had a free floating 24-inch match grade barrel with a fiberglass handguard and a flat-top receiver with a Picatinny rail for optics.
The bolt carrier was similar to an AR-10’s and the gun was designed specifically to fire 168-grain open-tip match cartridges with accuracy guaranteed at or under 1 MOA.
Initially, the SR-25 used AR-10 style 20-round magazines, but those were later replaced with “SR-25 pattern” steel magazines.
It didn’t take long for the rifle’s high mag capacity and fast engagement time compared to bolt action marksman rifles to attract U.S. Special Operations Command (SOCOM). They adopted the SR-25 as the Mk 11 Mod 0 in May, 2000. The SOCOM version had a shorter 20-inch barrel that could fire M118 and M118LR 7.62 NATO ammunition and had a quick-detach suppressor mount. It also had an 11.35-inch handguard rail system for mounting accessories, flip-up front sights and adjustable rear sights, along with an M16A2 stock and pistol grip.
During the Iraq War, the Marines ordered 180 Mk 11 Mod 1 rifles, which were Mk 11s equipped with the upper receiver of the M110 Semi-Auto Sniper System. This allowed the Mk 11 to have an URX modular rail system and flash suppressor on the barrel. These only saw limited use until the Marines switched to the Mk 11 Mod 2, which is simply a different designation for the complete M110 system.
In 2011, SOCOM began replacing the Mk11 Mod 0 with the SSR Mk 20, a sniper rifle variant of the FN SCAR rifle. The Mk11 was completely phased out by 2017.
The Ugly Sadness of the Colt 2000 Pistol
In the early 1990s, law enforcement in the U.S. was scrambling to catch up with firearms developments, with most officers and agents still carrying revolvers as their standard issue sidearms. Some departments, like the Los Angeles Police Department, followed the military’s example and switched to the 9mm Beretta 92 pistol platform (the M9 in the military), while others went with the SIG Sauer P226 or P229, or, the dominant Glock 17 and Glock 19.
Colt wanted to get in on the new police market with a modern semi-auto pistol offering of its own.
Stoner partnered with C. Reed Knight to design a prototype 9mm semi-auto pistol with a light frame that was suited to military and police needs at the time. Their prototypes were extremely promising and they sold the production rights for the pistol to Colt.
On the surface, the gun’s features line up quite a bit with what people expect from a modern 9mm handgun.
The striker-fired Colt 2000 had a polymer or aluminum-alloy frame and a locked breech with a rotating barrel (like the Beretta Px4). It was chambered in 9mm with a magazine capacity of 15 rounds—on par with the Beretta M9. Once the gun was sold to Colt, the gunmaker “finished” the design using its own engineers.
It had some really cool design features from Stoner and Knight—it was very easy to field strip, only requiring the slide to be locked back and a captive pin to be popped out. The slide then comes right off the frame and the entire two-piece trigger assembly can simply be lifted out. The trigger uses an innovative roller bearing system, patented by Knight and Stoner, which is actually an amazing idea that would provide a smooth and slick trigger pull, albeit one with a long pull. I said…would.
The handgun was introduced as the Colt All American 2000 at the 1990 SHOT Show with all the final changes added by Colt.
The original specs from Knight called for a 6 lbs. trigger, which is totally reasonable. Colt increased this to a whopping 12 lbs. trigger pull weight, which, combined with the long-pull trigger design of the gun, made for an unpleasant and inaccurate shooting experience.
Colt also extended the barrel and length of the grip frame. The gun was pretty darn ugly, and to me, looks an awful lot like a bastard love child born of a Browning Hi-Power and a Hi-Point 9mm.
Instead of actually manufacturing the gun, Colt had all the parts produced by an outside vendor and then the guns were assembled in Colt’s West Hartford facility. You can see where this is going.
Colt put a lot of effort and money behind the gun’s launched, believing it would be a game changer. And it seems the publicity campaign worked, judging by some of the print stories about the All American 2000 from the time.
“…the Model 2000 is a design which I believe promises to dominate autoloader development in the 21st century to the same degree that John Browning’s classic recoil-operated patent of 1898 has dominated the 20th century,” said Dick Metcalf, the handgun editor of Shooting Times magazine in 1991.
Despite Colt’s advertising efforts, the gun was deemed an inaccurate, unreliable mess almost out of the gate, leading to poor sales after launch. Additionally, the gun had to be recalled in 1993 due to safety issues.
Respected tactical expert Massad Ayoob called it “sad and ugly with pathetic accuracy.”
The failure of the Colt 2000 was complete when production ceased in 1994, sealing its fate as one of the most embarrassing failures in the company’s long history. It also stands as a sour last note for one of the greatest firearm designers to ever live.
Interestingly, the same year the Colt 2000 was introduced saw Eugene Stoner meet the legendary Mikhail Kalashnikov, designer of the Soviet AK-47 and AK-74 family of firearms, in Washington D.C. In addition to taking some interesting photos holding each other’s most famous gun designs, the two men reportedly discussed firearm design at length, despite a pretty severe language barrier.
Stoner passed away on April 24, 1997 at the age of 74. He was buried at Quantico National Cemetery in Virginia.