A Chronology of Development by Daniel E. Watters
The ORO publishes “SALVO Rifle Experiment: Preliminary Results.”
The BRL reprints “The Theory Of The Motion Of A Bullet About Its Center Of Gravity In Dense Media, With Applications To Bullet Design.”
CONARC Board No. 3 is officially renamed the Infantry Board.
Fairchild/ArmaLite officials receive their first official briefing on the 1956 SALVO trails.
CONARC HQ sends a letter to the Infantry Board titled “Study of Military Characteristics for a Rifle of High Velocity and Small Caliber.”
The BRL‘s Donald L. Hall and Billy S. Campbell publish “Upon Selecting an Optimum Rifle Round.” The study indicates that a projectile which tends to yaw soon after target impact also tends to result in greater kill probabilities. As a conclusion to this study, it is shown that a .22 caliber projectile weighing 50 grains could be made to result in good wound ballistic performance if the transverse moment of inertia is sufficiently low to encourage yawing immediately after impact. This results in the recommendation of a .22 caliber, 50 grain lead core projectile.
AAI files “Final Report – Small Arms Cartridge” concerning its fléchette development efforts. The report claims that a high velocity 10 grain fléchette is equally lethal as the .30 M2 rifle bullet out to 600 yards. Yet in terms of cartridge weight, five rounds of the saboted fléchette cartridge could be fired for each individual .30’06 cartridge. However, even at this early date, the issues of cartridge cost and individual accuracy are noted as potential problems.
Fairchild President Richard Boutelle goes on an African safari with US Air Force Strategic Air Command (SAC) commander General Curtis E. LeMay, radio and television personality Arthur Godfrey, and James Shepley, the head of Time-Life’s Washington bureau.
The Infantry Board extends the original 300 yard “ideal” to 400 yards in order to pacify certain CONARC members, and once again to 500 yards, to insure acceptance at the Pentagon. The finalized request calls for a 6 pound, select-fire .22 caliber rifle with a conventional stock and a 20 round magazine. The proposed chambering has to penetrate the issue steel helmet, body armor, and a 0.135″ steel plate at 500 yards, while maintaining the trajectory and accuracy of M2 ball from a M1 rifle, and equaling or exceeding the “wounding” ability of the .30 Carbine.
At ArmaLite, Stoner is more interested in developing 7.62mm NATO weapons, and is already working on the design of what was to become the AR-12 rifle (the father of the AR-16 and grandfather of the 5.56x45mm AR-18). Sources disagree as to who designed ArmaLite’s first SCHV prototype, the AR-11 (AKA: The “Stopette”). Essentially a scaled down version of Stoner’s 7.62mm AR-3 rifle chambered for the commercial .222 Remington, the AR-11 is credited to ‘Doc’ Wilson. The AR-11 proves to be too light, which combined with a high cyclic rate and the requested conventional stock, leads to difficulty in controlling automatic fire. Ultimately, the AR-11 prototype is wrecked when its barrel extension fails during testing. It is later claimed that the barrel extension was scaled down too far, weakening it. Remembering General Wyman’s favorable bent toward the AR-10 design, ArmaLite had also begun work on a scaled down version of the rifle. But this design, credited to John Peck, also uses the same small barrel extension as the AR-11. After the failure of the AR-11’s barrel extension in testing, work is discontinued on Peck’s design. Robert Fremont and L. James Sullivan are eventually tasked with starting from scratch in scaling down the AR-10 to .222 Remington.
Concurrently, Earle Harvey of Springfield Armory designs a lengthened .222 Remington case to meet the new 500 yard requirement. Remington loads 10,000 unheadstamped .224 Springfield cartridges: 9,500 with 55 grain projectiles and 500 with the 68 grain “M1 ball homologue.” Albert J. Lizza designs a rifle around the cartridge, using the best features of Harvey’s 7.62mm NATO T25 and T47 rifle prototypes, along with items inspired by the T22 (a full-auto variant of the M1 Rifle) and the T44 (pre-M14). It also appears that a T25 may have been converted to chamber the cartridge. Once Dr. Carten learns of Harvey and Lizza’s development, all further work on the .224 Springfield is ordered to cease. Ironically, Dr. Carten cannot claim that Springfield Armory is not in the weapon building business as he did two years earlier with Aberdeen. However, Carten is busy shepherding the T44 rifle into what is now known as the M14. No competition for resources (or attention) could be brooked.
George Sullivan files a patent application for the use of aluminum receivers in the design of a firearm.
Stoner provides a brief live-fire demonstration of the prototype AR-15 for General Wyman. CONARC formally requests the purchase of 10 test rifles for the Infantry Board (five days after the 7.62mm NATO M14’s official adoption is announced).
After a visit to Fort Benning, Stoner begins to tweak the .222 Remington round to fit the Infantry Board’s penetration requirements. First, Stoner and Sierra’s Frank Snow modify the .224″ 68 grain “M1 ball homologue” to 55 grains by shortening the bearing length and the boattail, while maintaining the original 7-caliber ogive and 9-degree boattail. The new projectile is also produced by Sierra. Robert Hutton uses Speer’s Ballistic Calculator to estimate the muzzle velocity need to provide the desired performance at 500 yards. The results indicate a muzzle velocity of 3,300 fps with the 55 grain bullet will be required. Hutton begins load development with IMR 4198, IMR 3031, and an unnamed Olin ball powder. Using a Remington Model 722 with a 22″ Apex bull barrel and a Lyman 25x scope, Hutton successfully perforates US helmets at 500 yards during a public demonstration. However, testing also indicates that the .222 Remington cannot achieve the required velocity without excessive chamber pressure. Stoner contacts Winchester and Remington about increasing the case capacity; Remington accepts the request. (This refusal is hardly surprising since Winchester had their own SCHV rifle and cartridge in the works.) The resulting cartridge is designated the .222 Special.
George Sullivan files a patent application for the forearm assembly used on the early AR-10 and AR-15 prototypes.
The T44E4 and T44E5 rifles are adopted as “US Rifles, 7.62mm M14 and M15.” (None of the heavy barrel M15 will ever be produced for issue prior to the M15 being declared obsolete in December 1959.) The USAF is the only service to decline use of the M14, and instead retains the M2 Carbine.
Springfield Armory publishes the report “Chromium Plating of Caliber .22 Barrel Bores.”
Springfield fabricates barrels for .22’06 simplex and duplex cartridges. These cartridges are based on the .30’06 case necked down to .22 caliber. The barrels are fitted to M1 rifles.
Psychological Research Associates publishes “Psychological Effects of Small Arms Fire on Combat Experienced and Non-Experienced Infantrymen” and “Psychological Effects of Platoon Weapons – A Questionnaire Study.”
CONARC invites Winchester to develop and submit a competing SCHV rifle. Ralph Clarkson, a member of Winchester’s in-house design team which developed the M1 Carbine, takes the assignment. Clarkson borrows heavily from David “Carbine” Williams’ shelved .30 Carbine design (completed two months after the adoption of the M1 Carbine). Working with David Mathewson, of the Mathewson Tool Company, Clarkson is able to complete the first firing prototype of the rifle in less than two months.
The Infantry Board forwards a letter to CONARC titled “Draft Military Characteristics for a Rifle of High Velocity and Small Caliber.”
Psychological Research Associates publishes “Psychological Effects of Patterns of Small Arms Fire.”
Laurence F. Moore of Aberdeen D&PS’ Infantry and Aircraft Weapons Division publishes the report “A Test of SALVO Rifle Materiel.”
Clarkson’s design, the Winchester .224 Light Weight Military Rifle (LWMR) is demonstrated at CONARC headquarters.
The US Army Chemical Warfare Laboratory (CWL) publishes “Wounding by Salvo Bullets.”
The LWMR is demonstrated to the Infantry Board at Fort Benning. The success of this demonstration leads the Ordnance Weapons Command and CONARC to order fifteen LWMR for further testing. However, it soon becomes clear that the new .224 Winchester cartridge will not meet the Infantry Board’s updated penetration requirements. Like its competitors, the .224E1 Winchester uses a lengthened .222 Remington case; however, the cartridge has a fairly short overall length (OAL). The stubby 53 grain projectile simply cannot retain enough velocity at longer ranges. As Stoner and Hutton had experienced before, Clarkson finds that he cannot load his .224E1 cartridge to a high enough velocity without encountering dangerously high chamber pressures.
Around the same period of time, the Infantry Board decides that Winchester and ArmaLite should cooperate to make certain that their ammunition will interchange between the competing rifles for future testing. The .224E1 Winchester’s case neck is lengthened to provide extra volume, and Winchester even chooses the same DuPont IMR 4475 powder used in the .222 Special. (At the time, DuPont owned a majority interest in Remington, while Olin owned Winchester.) However, the resulting .224E2 Winchester cartridge retains the same short OAL from the .224E1 in order to feed in Clarkson’s LWMR. Despite the fact that the .224E2 Win’s case is slightly longer than the .222 Special, ArmaLite is able to chamber their updated AR-15 to feed and function with both cartridges. In contrast, the Winchester entry can only feed their .224E2 cartridge. Subsequent trials are thus run using the Winchester cartridge.
SALVO II trials begin at Fort Benning. Among the weapons and cartridges tested are modified M1 rifles chambered for .22’06 simplex and duplex cartridges.
The CWL publishes “Incapacitation Criteria for Salvo Bullets.”
On behalf of the US Army, Albert J. Lizza files a patent application for the stock and action clamp of the Springfield .224 rifle.
Winchester ends contractual work on the double-barreled SALVO rifle.
by Daniel E. Watters, Small Arms Historian
Post questions or comments at The 5.56mm Timeline’s Facebook page.
Last Revised: 05/17/2009
This article was originally published at The Gun Zone — The Gunperson’s Authoritative Internet Information Resource. My friend and mentor Dean Speir has graciously hosted my articles at TGZ for nearly 16 years. These articles would likely have never appeared online without his constant encouragement and assistance.
With TGZ’s closure in early 2017, Dean encouraged me to find a new home for my scholarship so it wouldn’t be lost in the dustbin of the Internet. Loose Rounds has welcomed me with open arms. In the future, I intend to expand my legacy TGZ articles and add new contributions here at Loose Rounds.