• Manufacturer: LWL/USAMTU
  • Model: M21/XM21
  • Caliber: .308 Win (7.62x51mm NATO)
  • Barrel: Hand Selected National Match Barrels
  • Barrel Length: 22"
  • Twist: 1:10" RH
  • Magazine: 20 or 5 round detachable box magazine
  • Trigger: Specially tuned 4 1/2 pound match two-stage military trigger
  • Stock: Wood with glass impregnation
  • Metal Finish: Parkerized
  • Finish: Parkerized
  • Weight: 11.25 lbs (5.11kg)
  • Overall Length: 44.1" (1120mm)
  • Additional Notes: Rotating bolt, gas operated, air cooled, semi-automatic magazine fed rifle
    Redfield/Leatherwood 3-9x Automatic Ranging Telescope (ART)

As is common knowledge, the military forces in the 20th century had a very bad habit of disbanding sniper units and training between the major conflicts and after WWII it was no different for the US Army. So while they had gone through the effort and cost during WWII to first field the stop gap M1903A4 sniper rifle, and then develop and field the M1C and M1D sniper rifles, once the war ended, those rifles were stockpiled and packed away.

The M1C/D rifles made an appearance briefly in the Korean conflict, but they were never widely used and after those hostilities came to a cease fire, the M1C/D rifles were again packed away. Then the Vietnam conflict broke out and the US found itself in a guerrilla style war with a huge demand for qualified snipers and sniper rifles. This time around, the M1D rifles that were still around were not only old and out dated, but their 30-06 chambering was no longer the standard and the M1 Garand rifles were no longer in service. The US Army dabbled with scoped M-16s with very little luck, so finally a serious effort was made to develop and adopt a proper sniper rifle.


The US Army began its search in the same year that the USMC did, 1966, but the US Army did not go the route of a bolt action sniper rifle like the Marines, instead, they were believers in the semi-automatic and they started with modifying the M14. The M14 itself was an adaption of the original M1 but chambered in 7.62x51mm NATO (308 Win) and fitted with a detachable box magazine (DBM). They first tried using the M84 scopes from the old M1D sniper rifles and mounting them on top of a M14 with a modified swing over mounting system. The rifles were tested with both M80 and M118 match ammo, but the results were not very positive. The 2.2x magnification of the M84 scope was deemed unsuitable, the accuracy of the rifle with M80 ball ammunition was also unsatisfactory, and the scope mount, a hinged unit, was ruled deficient. But the National Match version of the M14 with M118 match grade ammo proved adequate and worthy of further development. So they continued with the program.

Because of the pressing need for sniper rifles in Vietnam, the Army actually deployed a good number of standard M14s with M84 scopes mounted in various different ways. This was done until a suitable permanent replacement system could be developed for the Army sniper program.

In 1964 James Leatherwood came up with a clever design for a mounting system that would allow a scope to be automatically adjusted when the zoom ring was changed. This was done via a cam system that would physically tilt the scope forward as the zoom power was increased. When he was based at Ft. Benning Georgia in 1965 the concept was presented to the Limited Warfare Laboratory (LWL) and a project was started to design a system that would work on a sniper rifle. An all-aluminum system was subsequently designed and then tested in 1967. It was called the Adjustable Ranging Telescope (ART) and was combined with a Redfield Accu-range 3-9x40mm commercial scope. You will probably recognize that this is the same scope the USMC adopted for their M40s during the same time. It was considered the best scope on the civilian market at the time.

ART I reticle

ART I reticle

ART II reticle

ART II reticle

The US Army had the scopes made without the tombstone ranging mechanism inside the reticle and instead had the scopes installed with a reticle that had marks on the stadia that covered 30 inches at 300 meters on the vertical and 60 inches at 300 meters on the horizontal. Since the reticle was located on the 2nd focal plane and did not grow and shrink with the power setting, it could be used to provide range estimation from 300-900 meters. The sniper would just zoom in until the marks on the vertical crosshairs would cover 30 inches, typically the belt line to the top of the head, and then look at the marks on the power ring to determine the range. At the same time, the cam would actually already be raising, or lowering, the scope to automatically compensate for the range at that distance. The entire unit performed as a system for rapid and accurate target engagement. Zoom in, hold for wind, pull the trigger. The cams were made to match specific cartridges and there were three different cams that could be switched out, one each for the M118 Match, M80 Ball and M2 50 BMG ammo.


Of course, all of the fancy auto-ranging ability of the ART system would do no good if the rifle could not perform adequately as well. The LWL contacted the United States Army Marksmanship Training Unit (USAMTU) to have them put together an accurized M14 for use with the ART. The USAMTU is where all of the competitive shooters for the Army are stationed and they came up with an extensive list of modifications performed on a National Match M14 rifle that included the following:

  • Disassembled down to the receiver
  • Barrels were selected for straightness and uniformity
  • Barrels were installed with minimum headspace on the chambers
  • Area of contact for the rod guide was knurled to prevent the guide from rotating on the barrel
  • Gas cylinder and band were screwed together as an assembly and internally polished to reduce carbon build-up
  • Piston was polished
  • Flash suppressor was reamed out to specifications shown to provide best accuracy with M118
  • Barrel and flash suppressor were machined for a perfect alignment
  • National Match stocks were treated in a vacuum sealed oven, baking at 300 degrees for an hour to remove all moisture from the wood, then the stocks were impregnated with epoxy and baked for an additional hour while held at 100 psi. Then the stock was placed in an oven to cure for 3 days. This was done to stiffen and eliminate any warpage or swelling due to weather changes.
  • Stock liner was removed to provide 1/8” of bedding compound in the recoil areas
  • Barreled actions were glass bedded in a two stage process to provide centering, and then pre-loading of the front part of the stock to dampen barrel vibrations.
  • Triggers adjusted to 4.5 – 4.75 lbs
  • Hand guard was cleared of the stock and anchored to the band
  • Gas cylinder lock was indexed to be finger tight at the six o’clock position
  • A new operating spring guide was installed
  • Cams, corners, and bearing surfaces throughout the mechanism were modified to provide smoother operation and uniform return of all moving parts
  • Rifles were then tested for accuracy and the ART mounted and zeroed

As you might imagine, these rifles were very accurate. They performed tests where they were getting 10 round groups at 900 meters that measured under 10”. The rifle was designated the XM21 The Army then sent 10 of these original XM21’s to Vietnam in 1967 for evaluation. There were several weaknesses found, but overall they were satisfied with the system as a whole. At the same time some M16s were being tested as sniping systems as well, but the smaller 5.56 cartridge could not match the long range capability of the XM21. The Army also considered bolt action rifles but elected to go with a semi-auto because it provided the ability to perform rapid follow up shots, rapidly engage multiple targets, allowed the sniper to better defend themselves and the M14 already was setup for night vision capability. They did recognize that the one major disadvantage was the flying brass that was ejected and could be a target identifier, but this was considered to be acceptable when compared to the advantages.



At about this same time the 9th infantry division requested help from the USAMTU in setting up a sniping program so in 1968 the AMTU sent over 10 instructors and then later sent over the first XM21 rifles for use with the 9th ID. Also, in early 1969 the AMTU sent over a batch of Sionics M14 suppressors for test and evaluation at the 9th ID sniper school with great success.

Finally in February of 1969 the XM21 was fully funded by the US Army and larger production began and the XM21’s were deployed in large numbers, about 50 per week being built to the exacting specs already mentioned. Officially the name remained the XM21 up until 1972 when the Army officially adopted it as the sniping standard and it became the M21. There were over 1300 XM21s used during the Vietnam conflict and while there were some failures, the rifles held up extremely well and served with distinction and great effect out to 900 meters.  After Vietnam, the sniping program in the US Army went dormant, again, until some interest was rekindled in 1976. The M21 was tested against the M40A1, M82, AR10, and some others and the M21 more than held its own and the Army elected to hold on to it as is. Once the official Sniper program was adopted by the Army in 1988, the M21 was replaced by a new bolt action sniper rifle known as the M24. There are still some M21’s in Army vaults around the country, but none are in wide spread use by the US Army today. Though the M21 still lives on having spawned some very successful offspring such as the XM25 and EBR.

As you can see from the comments below, the M21 holds a dear spot in many U.S. Army snipers hearts (me included), and rightfully so.



Loren Rogers

We had these in 1/75 Infantry (Ranger) back in the day (mid to late 1970’s). I did not carry one, but I remember them.

Sfc Brad Smith ret.

The m21 sys. was by far the best sniper weapon I ever used
until I started loading my own ammo. The school of the 25th
Id. had us qual. out to 1000m and we could not miss a single
target on the unknown rang to pass. I designed the patch for for snipers of the 25th ID. In 1968

Jim Remmel

My name is Jim Remmel, class of 8/1969 25th. Id. had one of the patches would it be possible to get another one or the design

Roger Dailey

I went to sniper school in Chu Lai Vietnam Oct/Nov 1970

Edwin Walteros

I used it in the Colombian army as a shooter weapon, when I belonged to the special forces

Storm Stone

I love the M21. It’s a beautiful thing, and I’ve got one myself.

Carl Dodd

I used a XM-21 sniper rifle for my last 7 months in Viet Nam. I loved that rifle. It was reliable and accurate in spite of the lousy conditions of that war. We snipers used our rifles in ways that we were never taught to use them because we just HAD to be inventive. I can remember before a full moon zeroing my day scope for targets out at 450 meters in a direction in which I knew that the targets would be coming at me, head on, with the moon’s light hitting them in the face. It was almost as good as them being pop-up targets that night. Nailed 4 of them and the rest ran away.


Thanks for the story with the rifle and your service! Sgt USMC 1990-1998

Keith Cunningham

I served with G Coy 75th Rangers – Recon Team Miami. I used the M-21 and still have the serial number. Any ideas as to if I could ever find out what happened to that rifle?

Mel Ewing

If it survived, chances are it is crated away in some storage facility as the rifles have not been surplussed or destroyed (that I know of). I’m not sure how to start the process of tracking it down.

Thomas Thorne

There isn’t any way that I know of to get a definitive answer for a particular serial number, you could always post the question along with the manufacturer and the serial number over on the M14 forum (http://m14forum.com/), someone there might be able to tell you for sure.

There were about 100,000 M14 rifles destroyed in the 90’s under the Clinton administration, and several thousand were surplussed out to the Philippines, Honduras (I believe), and a handful of other countries. I been told of M1 and M14 rifles that were battle lossed out during Vietnam that showed up during fighting in Afghanistan, so you never know what really happened to them.

Mike Hammer

Sniper school 5th sfg, 1982. M21 system Awesome shooting, 700 m one shot one kill, coke can center mass. Felt pretty good about myself that day after the range.
1/14 inf 25th inf div.

Blue 6

I spent my entire time as an active duty sniper (2009-2011) using a Navy variant of the M14 called a “PMR” (Precision Marksman Rifle), very much based on the USMC’s DMR version. Same Badger rings and a 4.5-14x Leupy FFP mil-dot. It was not/not accurized in any way, so none of the mods made to the XM21… but still awesome! The boarding team guys (all of us PMO’s were former boarding team guys) loved having us in overwatch. Right as I was rolling out we were transitioning to the EBR. Kind of a minor pain to clean, but you can’t go wrong with an M14! I’ve heard they cannot be de-mil’d because they inherently have characteristics associated with full auto by ATF, so the military has to destroy them instead of giving them to CMP. It’s a shame.

michael theis

howdy, was a combat sniper with the 4th inf 69-70, loved my xm-21, as a sniper in war, you will never forget,at 19yr old I felt a lot of pride, along with the kills I had, I remember the most, the guys I saved one day in the ashau valley. my rifle was a Winchester ,sure miss it. thank you. billings,mt d.co 1/12 4th inf 69-70

Alex P Chamberlain

A Chamberlain 5th Div. 1/11 infantry Recon serve as sniper 70/71 carried XM21 modified 14 loved my weapon trained at camp Eagle Viet Nam 101 airborne

revere reaper

I served in 3/172nd INF BN (MTN) VT ARNG in the 1980’s. We had six XM-21’s on the MTOE for each six man sniper section in each rifle company for a total of 18 sniper rifles in the battalion. Later I served in 505th ASA Co. at Fort Devens, MA. 10th SFGA would always display M21/M24’s on Armed Forces Day until the pulled up stakes moved to CO in 1995. They were equipped with M-3 Leopold Telescopes. Several surplus M24’s were sent to local P.D.’s under the NorthStar Program in the mid 1990’s under the Clintonistas until they got cold feet about militarization of Law Enforcement after Ruby Ridge, Waco, etc. There was even a stay-behind team of 10th SFGA Sniper Committee guys at Devens until 1996 providing training for the weapons to the local P.D.’s in New England, etc. Later, when I was in the Army Reserves at Devens, the former Sniper Committee Training NCO from 10th Group served as the sustainment training Manager for the MA ARNG and they used our reserve center as a staging area for quarterly sustainment training. The were equipped with M-24 Rifles and M-144 Spotting Scopes. That was about 1995 1997 as I remember.

Michael McClintic

Went to 1st INF Div Sniper School Di An RVN Dec 1969. Took my brand new XM21 out of the box and painted it camouflage before going to the 1000yd range. Used the Redfield 3×9 ART and PVS-2 Starlight scopes in the field. Carried 10 full M-14 mags in a claymore bag, heavy but worth it. A Co 1/16th(mech) Inf LRRP’s Best military Weapon I ever Used. SFC Michael McClintic (Ret)

Roger Dailey

i loved the xm-21, modified version of the m-14 with redfield 3×9 scope, match grade ammunition and pv-2 starlight scope. went through sniper school in Chu Lai south vietnam Americal division sniper school in October of 1970. A soldier by the name of Dennis Boucier was in the school also. I would like to know him again. a good man and a great sniper.

Russell Brown

Roger, I was in the first sniper school class in Chu Lai. After many years I found out that Dennis Boucier not only lived nearby but was working for the same company. Unfortunately I’ve lost contact with him. At one time he had a website for Americal snipers but it is no longer active.

Howard Kramer

I was top shooter in the second class of 9th ID snipers at Camp BearCat, November, 1968. I have 2 of the original ART’s and 2 AN-PVS-2’s to mount on an XM-21 built for me by a former AMTU armorer.

matthew J Ison

I attended The 1st Air Cav. snipers school in July 1970, In Bien Hoa. Our lead instructor`s were Master SGT. Bill Bearden & SFC Doug Shields. Along with several other, including a young SSgt. From Texas, who`s distinction was with a Gold Cup 45. The instructor`s all held the Distinguished Rifleman or Distinguished pistol badges. Sgt. Shields was also a member of the Presidents 100. After a couple of days, spend checking us out. The remainder of the class was issued our XM21`s with matching Redfield ART scopes & 2nd gen. starlight’s for night vision. That’s when school really begun. First up were classes explaining the rifles & equipment, and then time spend dry firing & proper rifle placement with sling use. Then the 25 meter rapid fire, using your sling wrapped tightly around your arm & wrist to help steady & secure the rifle, to maintain a reasonable shot group, then zeroing at 25 & 300 meters with iron sights. Next was zeroing the Redfield’s at 300 & 900 meters. We spend a lot of time being coached by our instructors, both in the classroom & on the range. We were taught how to setup an ambush, use the prc 25 field radios, for air support & artillery, basic medical & map reading. Ya could quite or be dro`d at anytime. In order to gradate, ya were tested on a steel target of a man’s head and chest at 600 meters. We had 20 rounds each, the idea was to see how many times ya hit the kill zone, I remember hitting him 17 times in the chest area (hits ), once in the head & once in the stomach ( considered misses) and one round ,the guy on the spotting scope didn`t see anything. I graduated in the middle of the class. The xm 21`s were exceptionally good rifle, never once did mine give me any reason , to question it`s accuracy and dependability.

Rich Anderson

I went to Fort Radcliffe 4 Division Sniper School in 1970
Loved that rifle school was tough only maybe half of our class made it through

Dale Hansen

I attended Sniper School at Camp Eagle in January of ’69. We received brand new, out of the box National Match M-14s and M-84 Scopes. I know where my rifle is today, but DoD’s policy is ALL M-14s are treated as fully automatic and therefore my chances of recovering my rifle are slim and none. Had a MG trying to get it for me, no luck. D-2/327 101st ABN. NFS!


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