brownell retro xm16e1
Robert A. Sadowski

Sometimes it is important to understand where you have been to know where you are and where you are going. Features on modern AR15-platform rifles like adjustable gas blocks, drop-in triggers, adjustable stocks, and M-Lock handguards evolved over time. The first “black rifle,” the XM16E1, is where the modern AR15 platform came from, and the Brownells XBRN16E1 (new this year) brings you back to the early 1960s when new words were added to our lexicon: M16, grunt, napalm, and Vietnam. It brings you back to the first Black Rifle. At SHOT 2018 Brownells introduced the Retro Rifle series, which are newly manufactured replicas of famous Eugene Stoner AR rifle designs. There are six rifles in the series and the XBRN16E1 is Brownells version of the first true M16-style rifle, called the XM16E1 by the U.S. before the platform was officially designated as the M16.

XM16E1 rifle in Vietnam
A U.S. soldier in Vietnam with an XM16E1 rifle. photo from

The U.S. military deployed in numbers that hadn’t been seen since World War II during the Vietnam War, and our troops used this rifle from 1964 through 1967.

During that time in country and under hard combat use, changes were made to the XM16E1 and the rifle was eventually reissued as the M16A1, which was in service with our troops from 1967 through 1982.

Brownells builds its replicas from new parts and with special attention paid to the features that differentiated these rifles from each other.

AR Timeline

The Brownells Retro Rifles series follows the timeline of the AR rifle beginning in 1955 with the BRN-10A, which is a replica of the original AR prototype designed by Eugene Stoner. This is a lightweight rifle chambered in .308 Winchester designed to replace the M14. Brownells produces two replica variants of this rifle. The BRN-10A with period correct brown polymer furniture and three-prong flash hider, and the BRN-10B with black furniture and an enclosed flash hider.

Though Uncle Sam passed on the BRN-10A when it decided to go with a smaller and faster round, some foreign militaries purchased the BRN-10B. The U.S. Military, especially the Air Force, was intrigued with the AR platform, but wanted it chambered in .223 Remington. As a result, Stoner and his team designed the Model 601, which was tested and fielded from 1959 through 1964.

brownell retro XM16e1's ergonomic grip
Grips have greatly evolved since the original A1 style pistol grip on this build. The flat sides are checkered polymer. Robert A. Sadowski

Brownells recreates this rifle as the BRN-601 and it is notable as not having a forward assist and being issued with green polymer furniture.

In 1964, the The XM16E1 replaced the Model 601 and became the first AR platform issued in mass quantities to the U.S. Army in Vietnam. Similar to the Model 601, the XM16E1 featured a forward assist and black polymer furniture. Brownells’ version is the aforementioned XBRN16E1.

In 1967, changes were made to the XM16E1 and the M16A1 was issued to all branches of the U.S. Military from 1967 through 1982. In the late 1960s a carbine variant was produced and called by various names depending on what branch of the U.S. military was using it. Part of the Colt CAR-15 series, sometimes called the Colt Commando, it was usually designated as the XM177 by the military and featured a carbine length barrel with a flash hider and a shortened or adjustable buttstock.

The M16A1 wasn’t officially designated as the standard service rifle for the Army, replacing the M14, until 1969.

The carbine version was in use with our military from 1967 to 1982 and was the predecessor to the M4 Carbine, introduced in 1994. Brownells’ version is the XBRN177E2 Carbine.

A Little More History

An original XM16E1 rifle
An original XM16E1 shown here with with two ammunition pouches, which were originally made for the M14, but were carried over in use for M16 magazines. The long pouch holds a bipod for the rifle and below is a standard M7 bayonet in its M8A1 scabbard. photo from

So now that we have the finer distinctions of the early family of AR rifles down, let’s take a look at where it fits in the military rifle timeline.

The U.S. Military was pretty much set on a new .30-caliber rifle to replace the M14 until the summer of 1961 when U.S. Air Force Chief of Staff, Curtis LeMay, encountered a few watermelons. LeMay saw a demonstration of the 5.56mm round with its 3,300-fps muzzle velocity in action on watermelons and the yaw of the 5.56mm as it penetrated the melons creating destructive wound paths.

LeMay became convinced the AR15 rifle and 5.56mm cartridge was the direction to go.

The XM16E1 was adopted by the U.S. Army in 1963 and began to be issued to troops in 1965 to replace the M14, which was an updated version of the revered M1 Garand with a detachable box magazine, full auto fire, and chambered in .308 Winchester (7.62 NATO). It proved too long, too heavy for marching through thick jungle, and the wooden stocks swelled in the intense humidity, ruining the rifle’s accuracy.

They were also pretty much uncontrollable in full-auto and burned through ammunition fast.

I have pals who got a free ticket to Southeast Asia thanks to President Johnson and some preferred the M14 due the power of the 7.62mm cartridge, but saw its liabilities in jungle combat. Others saw the upside of the M16 from the onset.

The new rifle that replaced it would eventually be referred to, generally, as the M16. Because of its dimensions, polymer furniture, and partial aluminum construction, it was much lighter than the M14 and allowed soldiers—who became known as grunts in Vietnam—to carry more rounds since it was chambered in a relatively new .22-caliber round that was much smaller and lighter per cartridge than the .308.

This was a big departure for the U.S. Military, which had been using heavy, .30-caliber rifles since Teddy Roosevelt lead the Rough Riders up San Juan Hill.

A High-Tech Amalgamation of Plastic and Aluminum

It is difficult to describe just how high tech the M16 was when it was introduced. It was made of high-tech materials like lightweight forged aluminum alloy and a polymer composite buttstock and handguard instead of wood. The use of these types of materials in firearms was unheard at the time. Today they are ubiquitous.

The M16 offered selective fire, like the M14 before it, and was much more controllable for most soldiers, though its efficacy in full-auto would be debated as the military has flip-flopped between including full-auto or three-round-burst settings on the platform over the years.

Ammo for the XM16E1 was toted in 20-round box magazines—the 30-rounders would come later.

brownell retro XM16e1's handguard cooling vents
Cooling vents on the top and bottom of the handguard were designed to vent heat from the gas system and barrel. Robert A. Sadowski

Inside, the new AR-platform rifles used an operating system that was quite different from the piston recoil rod system of the M14.

The M16 used a direct impingement gas system that was compact, lightweight, and reliable. The gun was touted to run so clean, it was referred to as a self-cleaning system. No cleaning kits were issued with the earliest versions of the rifles in Vietnam. That turned out to be a monumental mistake.

The Troubles

There was a change in the propellant used in the 5.56 ammunition between the time it was tested to the time it was issued, and it not only gummed up the works of the XM16E1 rifles, it left a number of our guys dead next to a disassembled guns on the battlefield. So the new M16s got the reputation of being a dangerous jam-o-matic made of plastic.

A Congressional investigation ensued and several aspects of the rifle’s design were changed. A chrome plated chamber and bore were added to eliminate stuck cartridge cases (something Stoner had included in his original design) and cleaning kits were supplied with a comic book manual showing how to disassemble and clean the rifle. No, really.

The manual was illustrated by cartoonist Will Eisner who had created similar manuals for the U.S. Army during WWII. The propellant in the ammo was also tweaked to burner cleaner, but the rifles still needed regular and thorough cleaning.

Brownells includes a reprint of The M16A1 Rifle Operation and Preventive Maintenance manual. You can also get a hardcover copy on Amazon.

Reliability of the rifle greatly increased, failures tanked, and the M16 was on its way to becoming one of the most battle tested and reliable firearm platforms ever designed. It went on to be refined with the M16A1, which included the forward assist, brass deflector, chrome plated bore, and the new 30-round magazines.

The U.S. Marine Corps adopted the M16A2 rifle in 1983 and it was later adopted by the Army in 1986.

brownell retro XM16e1's butt stock
(Left) The original M16 butt pad was a piece of plastic with serrations. It was replaced with subsequent design updates. The stock on the original M16 was polymer and concealed a cylindrical buffer tube. Robert A. Sadowski

The Modern Day Throwback

Flash-forward to 2018 and the XBRN16E1 from Brownells, a replica of the rifle issued from 1964 through 1967. What separates this rifle from the first AR-15 adopted, the Model 601, is the black furniture and classic triangular shaped handguard. The Aluminum heat shield is period correct without drain holes and the handguard uses a flat slip ring.

The pistol grip is in the classic A1 style with checkered side panels. The buttstock features a serrated plastic butt pad and Type D sling swivel. A beefed up butt pad that held a cleaning rod was added on the M16A2.

brownell retro XM16e1's featuring the forward assist
Top: The XM16E1 was the first M16 variant to include a forward assist. Bottom: Note the lack of a brass deflector. Early M16s with no brass deflector or forward assist are known as slab-side receivers. Robert A. Sadowski

The XM16E1 also features a period-correct three-prong flash hider but it also has a forward assist, something the original M16 did not have. The Brownells XBRN16E1 also has the privilege of history and experience built in. It’s like shooting a reproduction Winchester 1873. We tend to forgive the dated design features and let nostalgia take its course and just roll with it and the small updates make it a pleasure to shoot. It is also hard to replicate this rifle—it was a transitional model, so depending on when a given gun was made, they will have small differences in features.

brownell retro XM16e1's duckbill flash hider
The three-prong “duckbill” flash hider was replaced when it was discovered it easily got caught on vegetation and gear. Robert A. Sadowski

Like the originals, the barrel is 20-inches in length with a 1:12 twist rate with a chromed bore with a profile known as an M16 lightweight profile.

At the business end is a three-prong flash hider sometimes called a “duckbill” flash hider, which was replaced in later models because it was found to catch on jungle vegetation and gear too easily. It was replaced with the more familiar birdcage flash hider on the M16A1.

brownell retro XM16e1's magazines
The Brownells retro rifle comes with a period-correct 20-round magazine (top). SureFeed magazines from Okay Industries (bottom) supplied the Military with magazines. Robert A. Sadowski

I wanted an experience as close to the original as I could get, so I scrounged up new 20-round and 30-round magazines from OKAY SureFeed Magazines, which co-developed the original 30-round magazines with U.S. Army back in 1973. They still make excellent aluminum body magazines. Ask the gun fighters in our Military about SureFeed magazines and you’ll get the nod of approval.

A lot of shooters think a magazine just holds ammunition, but a quality mag can make the difference in a rifle’s ability to function. SureFeed magazine feature a 4-way anti tilt, self-lubricating follower. I also requisitioned some of the new SureFeed E2 aluminum body magazines with textured sides and low-friction feed lips so rounds align and feed smoother. Ok, so the new E2 magazines are not exactly an old-school, Vietnam era mags, but they sure work well.

brownell retro XM16e1's magazine
During the Vietnam War, 20-round metal body magazines were the most common; 30-round magazines started to appear in the early 1970s. Robert A. Sadowski

Besides the triangular handguard, the first thing I noticed with the XM16E1 was the lower receiver and the partial fence, a rounded bead that edges the top of the magazine well where the lower mates with the upper. This fence was added to reinforce the lower receiver.

The lower is 7075-T6 aluminum alloy machined by Aero Precision for Brownells. The upper uses a period correct forward assist with a tear drop button. Originally, the M16s issued to the U.S. Air Force didn’t require the forward assist.

The U.S. Army, however, specified the forward assist be required. The purpose was to allow the user to “assist” a round into the chamber if it quite get there on its own. The wisdom of forcing a round into a chamber has also been debated ad naseum, but many modern ARs still include a forward assist.

The original XM16E1 was the first rifle to incorporate the forward assist. You will also note the Brownells XM16E1 does not have a shell deflector. The shell deflector was added as a safety feature for left handed shooters with the M16A2 in the mid-1980s.

The finish on the Brownells rifle is a matte gray anodizing. The XM16E1 was the last rifle to actually chrome the BCG and the Brownells version has the same. On subsequent models it was parkerized. The charging handle is the late-model type with an improved design over the early triangular charging handle.

brownell retro XM16e1's rear sight and dial
Top: The rear sight was built into the carry handle and could be adjusted by pushing in the indent with a bullet tip and rotating the dial. Bottom: The rear aperture sight flips from close range to long distance settings. Robert A. Sadowski

The carry handle is an integral part of the upper receiver. Later, as optics became more of a common accessory on the platform, designs began including a top accessory rail onto which a removable carry handle could be attached.

The Brownells XM16E1 features a windage-adjustable A1 rear sight incorporated into the carry handle. The directional markings are recessed in the carry handle of the receiver. The rear sight flips between a large and small aperture for close or distant shooting.

brownell retro XM16e1's front sight
The A1 style front sight also contained the gas block. The front sight bead is adjustable for elevation using a special tool. Robert A. Sadowski

Since the twist rate is a slow 1:12, bullets weighing 55 to 60 grains or lighter are the rifling’s sweet spot. I suspected the 1:12 twist would also stabilize easy to find 62-grain FMJs. Original M16s used a 1:14 twist rate, which was soon changed to 1:12.

A 1:14 twist rate is only suited for bullet weights up to 50 grains. Faster twist rates are better from heavier bullets.

firing retro xm16e1 firing
The rifle in action. Robert A. Sadowski

Range Test

Using a rest with a target set up at 30 yards, I found the this retro rifle did not disappoint. With Hornady TAP FPD 55-grain bullets I consistently fired 0.5 inch groups. In fact all the 55- and 60-grain ammo grouped any where from 0.75- to 1.45-inches at 30 yards. I even tried 77-grain ammo and was served up perfect keyhole groups.

As I suspected the 77-grain ammo could not be stabilized by the 1:12 rifling. Not a show stopper just a characteristic of a gun that was built to replicate a rifle over 50 years old. After to 30 yard sight in I move my target out to 100 yards and using a rest and the iron sights was able to consistently shoot 5-inch groups which I thought was darn good using iron sights.

brownell retro xm16e1 target groupings
The rifle printed nice groups with a variety of ammunition. author photo

To recreate an exact replica of the XM16E1 is impossible since, as I said before, it was a transitional model that was tweaked and fine-tuned during the time they were issued, with early-issue models differing from rifles that were issued later.

Brownells had to decide on a balance of features to include on its Retro Rifle series version. For instance, the bolt carrier group of the XM16E1 was chromed in early models, but in later models in was parkerized. Brownells chose to recreate their XBRN16E1 with a chrome BCG.

The XM16E1 from Brownells allows you for a brief moment to walk in the jungle boots of a Vietnam GI. A grunt in the Vietnam War.


Action Type: Direct gas impingement, semi-automatic
Caliber: 5.56mm NATO
Barrel: 20 inches
OA Length: 40 inches
Weight: 6.6 pounds (empty magazine)
Stock/Grips: black polymer
Sights: adjustable front/rear
Trigger: single stage, tk pounds
Finish: matte black
Capacity: 20 + 1
MSRP: $1299
brownell retro XM16e1's selector switch
The selector switch is obviously for a civilian semi-automatic rifle, with positions for “Safe” and “Semi-Auto” only. Robert A. Sadowski

Performance Results: Brownells Model XBRN16E1

Ammo (.223 Rem.) Average Velocity (fps) Muzzle Energy (ft.-lbs.) Best Group (in.) Average Group (in.)
Hornady Steel Match 55-gr. HP 3023 1116 0.6 0.75
Fiocchi 55-gr. FMJ BT 3212 1260 0.95 1.175
Hornady TAP FPD 55-gr. TAP FPD 3044 1132 0.45 0.525
Winchester PDX1 60-gr. Split Core HP 2870 1006 1.4 1.45

Bullet weight measured in grains, velocity in fps, muzzle energy in ft-lbs., and average accuracy in inches for best five-shot groups at 30 yards.

NOTE: Data for the 77-grain ammo was not included, since the rifle’s rifling was not designed to handle that bullet weight.

brownell retro XM16e1's charging handle
Charging handles have evolved as the M16 design was refined. On the XM16E1, the charging handle has a more modern look that the original. Robert A. Sadowski
brownell retro XM16e1's eject port
Early model XM16E1 had a chrome bolt carrier group, like this one. Later models had a parkerized BCG. Robert A. Sadowski
a field stripped brownell retro xm16e1
Field stripping is the same as modern variants. Removing two pins separates the upper receiver from the lower receiver. Robert A. Sadowski
bayonet attached to the brownell retro ar
I found an M7 bayonet, which are still fairly easy to find. The M7 was was based on the M6 bayonet for the M14, but had a different mounted locking system and a larger diameter muzzle hole to fit the duckbill flash hider. Robert A. Sadowski
brownell retro XM16e1's and bandolier
The G.I. 7-pocket bandolier of the era was made olive drab cotton. It was intended for each pocket to hold a cardboard sleeve with two 10-round stripper clips. Most troops used the pockets to hold one 20-round magazine each. Robert A. Sadowski
brownell retro xm16e1 in hand
Even for a rifle design that is over 50 years old, the ergonomics are very user friendly. Robert A. Sadowski
brownell retro XM16e1s handguard
The triangular handguard also feels good and the flat bottom edge offers a steady rest. Robert A. Sadowski
brownell retro xm16e1 carry handle
The carry handle was built in, making it easy to carry the rifle when not in combat, though most were also outfitted with a sling and the actual usefulness of the carry handle has been debated. Robert A. Sadowski
brownell xm16e1 stripper clips being loaded into magazines
With the stripper clip inserted into the guide, you just press down on the cartridges to load the magazine. Grunts didn’t use these much in Vietnam, carrying plenty of extra magazines instead. Robert A. Sadowski