The 5.56 X 45mm “Timeline” – 1967

A Chronology of Development by Daniel E. Watters


Planned Fiscal Year 1967 DOD M16 Rifle Procurement

US Army 0
US Navy 19,237
US Coast Guard 700
US Air Force 65,000
US Marine Corps 18,294
Total 103,231

The USAF acquires 75 AR-18 for testing.

Howa Machinery Company of Nagoya, Japan buys the production rights to the AR-18 from ArmaLite.

Manufacture d’Armes de St-Etienne (MAS) of France begins development of a 5.56mm rifle. The project is led by Paul Tellie.

At Ruger, L. James Sullivan begins work on a scaled down M14 in 5.56mm. Several years (and modifications) later, it is released commercially as the Mini-14.

Singapore awards a contract to Kynoch in the United Kingdom for .223 Ball ammunition for both Army and Police use. Kynoch subcontracts to Hirtenberger Patronenfabrik in Austria for the brass cases and a Belgian company for the gunpowder.

NATO initiates a general feasibility study into caseless ammunition.

An ENSURE requirement is issued for a low-cost ($0.01 per round of ammunition contained) magazine capable of reliable one-time use in the M16A1 rifle.

Frankford Arsenal initiates the M16 Sight Enhancement Program to develop improved low-light sights, both iron and optical. Frankford’s Pitman-Dunn Laboratory also begins research into caseless cartridges.

Frankford Arsenal and Lake City begin the development of gilding metal clad steel (GMCS) jackets for the construction of M196 Tracer projectiles. This is the result of reported jacket failures with the M196.

The Naval Ordnance Laboratory produces a subsonic 5.56mm cartridge for use by SEAL teams. The projectile is a truncated lead slug. Another effort uses Sierra hollowpoints. Both are reportedly used for shooting sentry animals, but neither provides the desired terminal performance.

Nosler constructs 500 solid steel projectiles plated with bronze. The 41 grain projectiles are intended for testing by Frankford Arsenal.

The Deputy Secretary of Defense Vance approves Army Secretary Resor and General Johnson’s first, fourth, and fifth recommendations for the rifle program. Approval is withheld on the second and third pending the following information:

    1. A comprehensive cost/effectiveness study of a single rifle weapon systems versus the current M1, M14, and M16, or the alternative M14 and M16;
    1. A replacement and distribution schedule;
    1. NATO implications of replacing the M14 with the M16; and
  1. Details of proposed changes to the M16 with concurrence of the TCC, along with the availability of alternative powders.

A follow-up of the first survey and instruction visit to Vietnam is made by WECOM from January 17 through February 20, 1967.

COL Yount notes an “urgent” requirement for swabs, bore brushes, chamber brushes, and cleaning rods.

Test Plan on Military Potential Test of Weapon Lubricants” is published.

The closed-end “birdcage” flash hider is included in new production M16/XM16E1 rifles.

The CAR-15 Commando is type classified under the designations “Submachine Gun, 5.56mm XM177” (USAF – no bolt closure device) and “Submachine Gun, 5.56mm XM177E1” (Army – w/ bolt closure device).

D&PS publishes “Final Report on Engineer Design Test of Modified Flash Suppressor for CAR-15 Submachine Gun.”

Colt files the report “Delrin Charging Handle Latch Report.” The Delrin charging handle latch was designed in hopes of reducing user complaints concerning the charging handle unlatching while the weapon is firings. The “Commando” models are considered to be the worse offenders in this regard. However, it is eventually found that the Delrin handle latch is simply not durable enough for field use.

The PMR Office publishes “A Review of Primer Sensitivity Requirements for 5.56mm Ammunition.”

An US Army study and analysis of the internal ballistics mismatch of 5.56mm Ball and Tracer ammunition recommends that no changes be made despite the fact that 57 percent of the tracer ammunition was mismatched.

Colt’s Foster Sturtevant receives US Patent #3,301,133 titled “Mechanism for Changing Rate of Automatic Fire.”

Colt receives waiver on surface finish of 6,000 bolt carriers.

The US Navy orders eight belt-fed Stoner 63A LMG for field testing by the SEALs in Vietnam.

FN builds five additional CAL prototypes.

NWM and its parent company Mauser – Industrie Werke Karlsruhe AG (IWK) of Germany introduce a quartet of 5.56x45mm loads to support the Stoner 63. This includes a 63 grain tungsten core AP load, a 700m-range tracer, and a training blank. Most interesting is the 77 grain FMJ load (2,722 fps), which requires a 1-in-7.8″ twist barrel.

ACTIV publishes “Evaluation Plan-XM148 Grenade Launcher.” The primary purpose of this evaluation is to determine if the XM148 grenade launcher will operate effectively in the hands of the average soldier under combat conditions. A secondary purpose is to determine durability, maintainability, and future combat service support requirements. The evaluation of the XM148 grenade launcher is being conducted at the request of the Office of the Assistant Chief of Staff for Force Development and the CDC.

The HEL publishes “A Human Factors Evaluation of the Two SPIW Prototypes.”

Since the Marines of III MAF will soon be issued the XM16E1 rifle in Vietnam, rifles are shipped to Camp Lejeune, the Marine Corps Schools at Quantico, and the Staging Battalion at Camp Pendleton for testing. The rifles will be used by selected personnel in conjunction with contingency training.

A tentative agreement between the Army and Colt is reached. This will require a 5.5 percent royalty, a $4 million lump-sum payment, and commitments to purchase from Colt. This involves Colt receiving any requirements in excess of an educational order quantity for the first three years as a part of the Army’s five-year procurement plan. This agreement does not include the XM177.

The XM16E1 rifle is classified as “Standard A”. Its designation officially changes to “Rifle, 5.56mm, M16A1.”

Chief of Operations Research Dr. Payne sends a memorandum to Under Secretary of the Army David E. McGiffert titled “Modifications to the M16.”

General Johnson sends a memo titled “NATO Impact of SAWS Decision” to Secretary Resor. While the standardization of the M16A1 is a concern to fellow NATO allies, Johnson suggests that US troops assigned to NATO will not replace their M14 rifles prior to FY 1972. This would place the changeover safely behind the January 1968 expiration of the NATO standardization agreement.

CINCPAC Admiral Sharp restricts further issue of M16A1 rifles to other nations’ troops. After discussions with the commander of the US Military Assistance Command – Thailand (MACTHAI), Admiral Sharp relents and recommends that the Thai Army receive 900 out of the 4,000 M16A1 originally allocated by the JCS. The rifles will be taken from March production deliveries.

The US State Department’s Office of Munitions Control reapproves the export sale of 18,000 AR-15 and 2,300 AR-15 HBAR M1 by Colt to the Republic of Singapore. This creates a political firestorm when news of the sale becomes public. While Colt claims that the export rifles will come from expanded production quotas, the sale not only angers those who think these rifles should go to US troops, but also US allies with troops stationed in South Vietnam. For instance, South Korean troops are still armed with surplus M1 rifles.

Winchester/Western proposes altering the direct gas system of the M16 to a short-stroke gas system.

The SPIW executive committee reconvenes. To support a future reactivation of the program, AAI is awarded a “nominal fee” contract to continue improvements of their SPIW candidate. Two of the second-generation SPIW prototypes are returned to AAI for further modification and experimentation.

Aberdeen’s D&PS publishes “Final Report on Engineer Design Test of Special Purpose Individual Weapon.”

The Stoner 63A system begins field-testing in South Vietnam with Lima Company, Third Battalion, First Marine Regiment, First Marine Division. Most Marines are issued the rifle, while officers and NCOs are issued the carbine. A couple of the Bren-style LMG are mixed in for squad automatic use, while the Weapons Platoon receive the belt-fed LMG and MMG variants. During the first two weeks of combat, 33 malfunctions are reported, most being failures to feed, fire, eject, and extract. During one night ambush patrol, only one of the four Stoners works reliably. The culprits are determined to be the weapons’ tight tolerances combined with the fine sand of the coastal plains in their Area of Operations. In response, Lima Company attempts to break-in their weapons with extended live-fire drills. For the most part, this plan succeeds, in conjunction with the delivery of a different production lot of ammo.

General Johnson issues memo CSM 67-96 “Army Small Arms Program.” It is intended to provide guidance for the formal establishment of the Army Small Arms Program and future small arms weapon development. Among the projects suggested, the Chief of Staff directs investigation and test of alternative methods for launching 40mm grenades. He specifies consideration of grenades launched from the muzzle as complementary or as an alternative to the XM148 and M79.

President Lyndon B. Johnson promises 25,000 M16 rifles to the Republic of Korea (South Korea).

The allocation of M16A1 rifles for ARVN and ROK maneuver elements is reinstated.

Secretary McNamara announces that 4,000 M16A1 rifles with spares and ammunition has been funded in the FY 1967 Thai MAP. McNamara’s opinion is that these rifles, plus the 500 previously delivered to the Thai Army, will “establish a pool from which M16A1 rifles can be supplied to all RTA units actively engaged in internal security operations.”

The PMR office notes seven continuing issues with the M16A1: 1) Sources of alternate propellants; 2) High cyclic rates; 3) Chamber corrosion; 4) Barrel twist; 5) Fouling; 6) Tracer requirements; and 7) Product improvements.

Based upon newspaper reports of troubles with the M16A1, Kantany imposes mandatory inspections (Product Inspection Type B – PIT B) at Colt in selected areas. These inspections are expanded through the next five months. A vicious cycle ensues as inspections are performed for a period of time, stopped after good quality history is experienced, and then reinstated based upon additional adverse publicity, results of contractor decision verifications, or any other input indicating the need for closer control of component quality.

The US Army completes distribution of the XM177E1 to troops in Vietnam.

COL Yount sends message titled “Type Classification XMl77E1 Submachine Gun (CAR-15 SMG).”

Colt agrees to add the XM177 for a total of $4.5 million and 5.5 percent royalty plus a provision initially suggested by the Army for a higher royalty (11 percent) if the procurement of rifles exceeds 1.85 million in the FY 1968-72 period.

TECOM sends message titled “Type Classification of Submachine Gun (CAR-15).” TECOM concurs with a recommendation from AMC to type classify the XM177-series for temperate zone use. However, TECOM withholds comment on the suitability of the XM177E2 until a test of the product improvements is conducted.

The BRL publishes “Pressure Measurements: Caliber 5.56mm Cartridge.”

ODCSLOG sends a memo titled “M16A1 Rifle Ammunition.”

The USMC asks Cadillac Gage to upgrade another eight of their early Stoner 63 to the 63A standard.

Arthur Miller, Charles Dorchester, and George Sullivan file a patent application for the design of the upper handguard attachment of the AR-18.

384 Colt/Realist 3x scopes arrive in Vietnam for mounting on M16A1 rifles.

Mixed reports also come back concerning the XM148 grenade launcher. While M79 users quickly welcomed the rifle/grenade launcher concept, the XM148 proves completely unsatisfactory under combat conditions. Users complain that the quadrant sight is prone to snagging in brush, and worse, that the sight is difficult to use with any accuracy. Also listed as snag prone are the extended trigger and trigger bar. These can be bent or broken simply by opening or closing the rifle’s receiver during/after fieldstripping. The separate cocking lever is quite unpopular due to the 30lb (~14kg) force required to cock the weapon. Within a few months, units with the XM148 are clamoring to have their M79 reissued. This is significant as most M79 users are only issued a M1911A1 pistol as backup for their grenade launcher.

AAI publishes “Design, Development and Fabrication of a Multi-Shot, Automatic Launching Device.”

HQ USARV requests technical assistance with the XM148 grenade launcher. The technical team sent in response stays in Vietnam from April 27 through May 18, 1967. The primary purpose of the survey is to evaluate and correct problems with the XM148 grenade launcher, but the team also examines large numbers of M16 rifles in the hands of troops to determine the status of maintenance, the availability of cleaning materials, and the condition of rifle barrels and chambers. The survey team concludes that rifle maintenance and the availability of cleaning materials has improved considerably and that the major remaining problem is deterioration of rifle barrels caused by chamber pitting and the accumulation of copper fouling. It is estimated that approximately 10 percent of the M16 in Vietnam will require a barrel replacement every three months. To reduce the rate of barrel deterioration, the team recommends speeding up deliveries of the recently adopted improved lubricant MIL-L-4600A (LSA), and chrome plating the rifle chambers.

In the NATO Standardization Meeting of Panel III, the British propose that a study be instituted to determine the desirability of accepting the 5.56mm as an additional standard NATO round. All nations vote in favor of the study at that time.

The Preparedness Investigating Subcommittee of the Senate Armed Services Committee holds hearings on the Army’s procurement and distribution of the M16. Testimony is heard from ASA(I&L) Dr. Brooks and MG Henry A. Miley, Jr., Director of Materiel Acquisitions, ODCSLOG. During the hearings, Subcommittee Chief Counsel James T. Kendall alleges that there are widespread rumors that the rifles being sent to Singapore will be diverted to the People’s Republic of China. Senator Margaret Chase Smith (R-ME) also claims to have heard the rumors. Dr. Brooks and MG Miley both deny having heard such rumors.

All live firing in Vietnam-oriented Army infantry training has been converted from the M14 to the M16A1 rifle.

The South Vietnamese military receives the first deliveries of M16A1 rifles. However, there are only enough to equip the Airborne and Marine battalions of the General Reserve.

The Air Force Marksmanship School publishes “Test of M16 Rifle Barrels with Chrome Chambers.”

TECOM begins testing of lubricants for M16A1. The relative technical merits of VV-L-800, Dri-Slide, MIL-L-46000A (LSA), and NRL-4002-36 are compared.

COL Yount sends message titled “Effectiveness Evaluation of XM177/XM177E1 SMG.”

TECOM sends memo titled “Test Directive for Product Improvement (PI) Test of the Submachinegun, Cal. 5.56mm, XM177E1” to the Commanding Officer of Aberdeen Proving Ground and the USAIB President.

Negotiations begin for the procurement of 510 XM177E2 for the Studies and Observation Group (MACV-SOG).

Lima Company 3/1 1st MARDIV requests that the test period for their Stoners be extended by an additional month. This request is approved. However, the Bren-style LMG is removed from issue as being redundant.

The USMC places an order with Cadillac Gage for additional spare parts and ammunition linking devices to support the Stoner 63A.

All other USMC maneuver and reconnaissance units in Vietnam have been issued the M16A1.

On May 3rd, Representative L. Mendel Rivers (D-SC), Chairman of the House Armed Services Committee, orders the formation of the Special Subcommittee on the M16 Rifle Program. The Subcommittee is comprised of Representatives Richard Ichord (D-MO), Speedy O. Long (D-LA), and William G. Bray (R-IN).

The May 13th issue of Paris Match magazine publishes photos of dead Marines with field stripped (or otherwise hors de combat) M16A1. The photos were taken by French photo journalist Catherine Leroy during the recent battles for Hills 861 and 881 (North and South) near Khe Sanh (24 April-5 May 1967).

Two days after the Paris Match photos are published, the Special Subcommittee on the M16 Rifle Program opens hearings.

Rep. James J. Howard (D-NJ) reads to Congress a letter reputed to be from a wounded Marine asserting that many Marine fatalities at Hill 881 were due to jammed M16A1. Rep. Howard requests that McNamara answer the charges and declares his dissatisfaction with the reply received from Marine Corps Chief of Staff LTG Leonard F. Chapman, Jr. LTG Chapman notes that some malfunctions were reported, but they were not out of line other weapons when first introduced. LTG Walt, just having returned from the South Vietnam as commander of the III MAF, describes the M16A1 as the best rifle ever issued to the USMC and that jamming is the result of soldiers and Marines failing to keep the rifle clean. USMC Commandant General Wallace M. Greene also holds a press conference to defend the M16A1.

The King of Laos, Sri Savang Vathana, makes a request for M16 rifles, stating that he would like to equip one elite Groupe Mobile (GM), ~1,800 men, with the rifles. When CINCPAC Admiral Sharp inquires about the matter, the Deputy Chief of the Joint US Military Advisory Group-Thailand (JUSMAG-THAI) voices his objections. However, the Deputy Chief will be willing to drop his objections if the delivery is deemed politically necessary. The JCS indicates that 2,000 M16 rifles could be made available from September 1967 production, if Admiral Sharp approves the transfer.

A chrome-plated chamber is approved for the M16 rifle family. A fully chromed bore will not be approved until later.

Colt changes the finish of the firing pin from electrolyzed to hard chrome.

The US Army Arctic Test Center publishes “Engineer Design Test of Preservative Lubricants for Small Arms Weapons under Arctic Winter and Spring ‘Break Up’ Conditions.”

The SEALs order an additional 36 Stoner 63A LMG. In contrast, the remainder of L/3/1 1st MARDIV’s Stoners are exchanged for M16A1 at the end of their test schedule.

Arthur Miller, Charles Dorchester, and George Sullivan receive US Patent #3,318,192 titled “Locked Action Rifle for Automatic and Semi-Automatic Selective Firing.”

ACTIV publishes the report “XM148 Grenade Launcher.” US Army Maneuver Battalions throughout Vietnam were sampled to record user reaction to, and experience with the weapon. Deficiencies of the XM148 were the poor position and projection of the sight, difficulty and unreliability in operation of the cocking and firing mechanism, unsatisfactory pointing and handling characteristics, slowness in loading, and degradation of mobility in some circumstances. Additional deficiencies were slow rate of fire, unreliability of functioning, and inadequacy of safety features. The XM148 is deemed unsatisfactory for further operational use in Vietnam. It is recommended that the XM148 grenade launcher be withdrawn from US Army Maneuver Battalions and that the M79 grenade launcher be reissued on an interim basis until an improved launcher or a new system is developed. Research and development activities should be continued on systems to provide soldiers in small combat units with the dual capability of point and area target destruction in a single individual weapon.

The Ichord Subcommittee visit Vietnam to examine M16 reliability issues first hand.

Retired Army Colonel E.B. Crossman files “Report of Investigation of M16 Rifle in Combat” with the Ichord Subcommittee. Comprised of 250 personal interviews with Army and Marine units in Vietnam, it reports that roughly 50 percent of the troops have experienced serious malfunctions with their XM16E1 rifle, of which 90 percent were failures to extract. The cause of these malfunctions was not determined. Other observations are that: 1) The bolt closure device is used frequently enough to justify the Army’s insistance upon this product improvement; 2) Extractors and extractor springs require replacement fairly often; 3) While there is no general shortage of cleaning and preserving equipment, many individuals are short of the critical cleaning rod and chamber brush; 4) Approximately 50 percent of the men preferred the M14. Most of the men who want the M14 feel that it is a more reliable rifle and are concerned about the M16’s possible malfunctions in combat; and 5) Many cases of a stuck or jammed selector lever are reported. COL Crossman recommends to Rep. Ichord that an immediate investigation be conducted of ammunition design and manufacture, rifle design and manufacture, and maintenance in the field to determine the cause and cure for failures to extract.

III MAF institutes a biweekly malfunction report for the M16A1.

Colonel Yount is relieved of his duties as PMR. Colonel Alvin C. Isaacs is ultimately named as Yount’s successor. Until Isaacs can assume the post, LTC Robert C. Engle serves as acting PMR.

Deputy Secretary of Defense Vance resigns.

A Defense study concludes that a one-rifle system based on the M16A1 will be the most cost-effective for the period 1969 to 1980.

An In-Process Review of the IRUS-75 study is conducted.

The US Army’s ammunition procurement request for FY 1968 is increased to 708 million cartridges at a total cost of $73.2 million.

TECOM publishes “Military Potential Test of Weapons Lubricants.” The report recommends use of MIL-L-46000A (LSA) for M16A1 at temperatures above 0F.

The first shipments of LSA for purposes of rifle lubrication (as opposed to its original use for the M61A1 Vulcan) are shipped to South Vietnam.

M16A1 maintenance instructions are revised to recommend liberal use of lubricant on rifle.

WECOM sends a letter titled “Lubrication and Preservatives for M16A1 Rifle” to commanders in South Vietnam detailing changes in recommended rifle lubrication.

New USMC testing also recommends LSA for general use, with Dri-Slide retained as a supplemental lubricant for sandy areas.

TECOM directs that a product improvement test of the redesigned buffer be conducted using the old and new buffers with the objectives of comparing cyclic rates of fire and of comparing the bolt rebound upon closing (bolt carrier bounce).

Springfield Armory releases the report “Erosion Test on 5.56MM Rifle Barrels, Small Arms Weapon Study (SAWS).” Results are reported on limited erosion testing of three barrels each fabricated from AISI/SAE 4150 steel and Cr-Mo-V steel, with and without chromium plated bores. Tabulated test data include projectile velocities, land and groove diameters, temperature versus time curves, and ammunition expenditures. The unplated 4150 steel barrels were rejected after approximately 1,900 rounds were fired at 60 shots per minute. Rejection was based upon the projectile instability criterion, exceeding 15-degree yaw. The chromium plated 4150, and the unplated and chromium plated Cr-Mo-V barrels withstood 3,600 rounds fired at rates of 60 and 80 shots per minute.

Springfield Armory also publishes the report “Development of a Stellite-Lined, Chromium-Plated Barrel for 5.56MM Machine Gun.” Springfield Armory’s procedure for the design and fabrication of a Stellite-lined, chromium-plated barrel for the Stoner 63 machine gun is described. Results of erosion tests of the Stellite-lined barrels, standard barrels, and two other types of barrels show that the Stellite-lined barrels are superior in erosion resistance. One of the Stellite-lined barrels was fired 43,994 rounds prior to rejection. A maximum of 12,476 rounds was fired from one of the standard barrels prior to rejection. The two other types of barrels – a standard barrel with a nitrided bore and a barrel of two-piece construction – were fired 29,874 and 990 rounds, respectively, before rejection. The two-piece barrel has an 18-inch forward section made from Cr-Mo-V steel and the rear section, including the chamber, is made entirely from Stellite. All barrels were rejected on the basis of the projectile instability criterion – 15 degrees yaw of 20 per cent of the projectiles fired. All barrels were fired at an average rate of 200 shots per minute.

Colt’s Robert Fremont files patent applications for a partially curved 30 round magazine and a disposable plastic magazine.

A private research firm, Planning Research Corporation, files a report claiming that given sufficient development a SPIW would be more cost-effective than other available infantry small arms. It recommends that the AAI SPIW rifle and DBCATA be chosen for further development.

The brief “Six-Day War” leaves Israel troops unimpressed by the reliability of theirFN FAL and FALO. Testing for a new rifle begins. After testing the M16A1, Stoner 63, HK 33, and others, it becomes clear that nothing matches the reliability of their Arab enemies’ Kalashnikov rifles. IMI sets about to create an improved clone. With the assistance of Interarms and Valmet of Finland, Israeli Galili and Yaacov Lior combine Valmet M62 receivers, Colt barrel blanks, FAL folding stocks, and a modified Stoner 63 rifle magazine to create the Galil.

A small development requirement for a 40mm detachable grenade launcher for rifles is approved by ACSFOR LTG Arthur S. Collins, Jr.

FN builds a pair of 40mm grenade launcher prototypes for the CAL.

The US Army finally obtains the manufacturing rights and the TDP for the M16 and XM177-family. This is necessary for the establishment of additional production sources. Colt employees promptly prove the Army’s point by going on strike in protest the very next day. The Government agrees to pay $4,500,000 in cash and a royalty of 5.5 percent on all rifles and parts purchased from companies other than Colt. In addition, the Government agrees to purchase 632,500 rifles from Colt through April 1970.

The Federal Mediation Service summons both Colt management and labor representatives to Washington in an effort to end the strike.

Deputy Secretary of Defense Paul H. Nitze issues a memorandum directing a technical evaluation and field study of the M16. The is to determine whether any major deficiencies exist, and if so, recommend corrective action.

Thirty XM177E1 barrels with chrome-plated chambers arrive in Vietnam.

ACSFOR LTG Collins publishes a draft of the US Army Small Arms Program (ARSAP).

USMC announces that LSA will replace VV-L-800 as the standard rifle lubricant and that Dri-Slide will not be retained in the supply system.

Remington sends a memo titled “Development of Caliber 5.56mm Ammunition.”

Lake City begins development of a steel 5.56mm cartridge case.

CDCEC publishes “XM148-40mm Grenade Launcher Evaluation Report.”

The US Army briefs representatives from private industry concerning what is to be later titled the Grenade Launcher Attachment Development (GLAD) Program. This briefing is intended to solicit interest in the development of alternative grenade launchers to the XM148. Out of 17 companies, only seven express interest: AAI, Aerojet General, Colt, Chrysler, Ford Motor Company’s Aeronutronic Division, Harvey Aluminum, and United Aircraft.

FN submits a CAL prototype to Sweden for testing.

The strike at Colt ends.

USMC Commandant General Greene sends a message to AMC critical of the quality of M16A1 rifles.

Yet another batch of comparison testing is conducted between 1-in-12″ and 1-in-14″ twist barrels. 2,000 new M16A1 rifles are used, evenly divided as to the installed barrel’s rate of twist. The 1-in-14″ barrels exhibit double the average extreme spread of the 1-in-12″ barrels at 100m.

At the request of WECOM, Aberdeen begins product improvement testing of the XM177E2. The product improvements of the XM177E2 are:

    1. Chrome-plated chambers to minimize corrosion and promote extraction;
    1. 1.5″ longer barrel and grenade launcher spacer for mounting XM148 grenade launcher;
    1. Delrin charging handle latch to minimize wear on upper receiver;
    1. Handguard slip ring reshaped to provide ease of assembly;
    1. Cadmium-plated slip ring spring to minimize corrosion;
    1. Shot-peened upper and lower receiver to minimize corrosion;
    1. Nylon coated buttstock and release lever to minimize corrosion; and
  1. Although the buffers of the XM177E2 and those of the XM177E1 in this test are the same, they represent a different design from those used by the CAR-15 SMG in the SAWS test.

In addition, Aberdeen will evaluate weapon performance when using both IMR 8208M and WC846-loaded cartridges with both ball and tracer projectiles. The test results will also be evaluated regarding suitability of the XM177E2 product improvements for application to the M16A1 rifle.

On behalf of COL Isaacs, William C. Davis sends a memo titled “Approval of Test Plans for Product Improvement Test of Sub-machine Gun, Caliber 5.56mm, XM177E2” to the Commanding Officer of Aberdeen Proving Ground. The letter requests that test firing of the XM148 Grenade Launcher mounted on the XM177E2 be included in both the USAIB and D&PS test plans. The test should determine if it is technically feasible and safe to fire the XM148 when attached to the XM177E2.

TECOM sends a letter titled “Approval of Test Plans for Product Improvement Test of Sub-machine Gun, Caliber 5.56mm, XM177E2” to the Commanding Officer of Aberdeen Proving Ground and the USAIB President. Forwarding the OPMR‘s request, the memo requests that safety release for firing the XM148 from the XM177E2 be provided by September 29.

Frankford Arsenal completes development of case hardness standards for the 5.56mm.

Frankford Arsenal sends the letter “Quality Assurance Provisions for 5.56mm Cartridges.”

CDCEC publishes “Infantry Rifle Unit Study (IRUS-75): Phase I, Field Experiment.”

The PMR Office distributes a fact sheet titled “Chamber Brush–M16A1 Rifle.”

A multi-service field survey is conducted by the Directorate for Inspection Services (DINS), Office of the Assistant Secretary of Defense (Administration). Out of 2,100 troops interviewed, only 38 wished to trade in their M16 rifles. Of these, 35 wanted an XM177-variant.

All new production M16 rifles and spare barrels are now manufactured with chromed chambers.

TECOM begins comparison testing of old and new-style buffers.

As a result of the USMC Commandant’s letter, representatives from WECOM, Rock Island Arsenal, the Headquarters of the Defense Supply Agency (DSA)/Contract Administration Services (CAS), and DCASD-Hartford conduct an inspection of the rifles located at the USMC Supply Center, Barstow, California. Of the 14,676 rifles inspected, 326 defects are found in 320 rifles. Thirteen of the defects are classified as being in the “major” category. In approximately the same time frame, representatives of WECOM and Colt proceed to Camp Forster, Okinawa and reinspect the 172 rifles set aside as defective by the USMC as a result of their inspection of 39,512 rifles. The team concurs with the USMC‘s findings and classifies 12 of the defects in the “major” category. Also, an evaluation of rifles representing this month’s production is conducted at Letterkenny Depot and at Colt by a WECOM/Defense Contract Administration Services (DCAS) team. A total of 15,460 rifles are inspected, and 281 are found to be defective, 20 of which are in the “major” category.

The OCSA sends a memo to Secretary Resor titled “M16 Rifle Testing.” Inside are the results of the first full scale-testing of the Sturtevant buffer.

The Department of the Army submits the report “Summary of Facts Concerning Comparative Evaluation of AR-15, M14, and AK-47 Rifles.”

The brochure “M16 PM Indicators for Inspectors” is published.

Three contract modifications are awarded to Colt for 124,772, 74,414, and 43,530 rifles. Together, these are worth $25,871,701.

AMC HQ sends a memo titled “Significant Elements of Second Source Procurement Plan – M16 Family of Rifles.”

ACTIV publishes the report “CAR-15 Submachine Gun (XM177E1).” An evaluation of the CAR-15 Submachine Gun (XM177E1) was conducted at the request of the Office of the Assistant Chief of Staff for Force Development and Headquarters, US Army, Vietnam. The purpose of the evaluation was to determine the employment and performance of the XM177E1 in combat, assess its suitability for use in Vietnam, and to recommend a Basis of Issue. Major combat unit throughout Vietnam were surveyed through interviews, questionnaires, and special reports. Data on user experience, opinion, recommendations, and suggestions were recorded and analyzed. The XM177E1 was found to be reliable and durable, with no major deficiencies. It is deemed suitable for extensive employment in Vietnam. Combat leaders and their troops at all levels desire the weapon. The report recommends that: 1) The XM177E1 be issued as a standard weapon in Vietnam; 2) The M3 SMG be eliminated from the Army’s inventory; and 3) Combat Developments Command develop a Basis of Issue plan by TOE line number.

CDC publishes “Infantry Rifle Unit Study 1970-1975 (IRUS-75): Phase I.”

The Philippine Secretary of National Defense, General Ernesto S. Mata, makes an urgent request to the Chief of the Joint US Military Advisory Group-Philippines (JUSMAG-PHIL), for 200 M16 and 90,000 rounds of ammunition for the Philippine Constabulary (PC) as soon as possible. These are for use against the Huks in the Tarlac and Pampanga Provinces, which are in the area around Clark Air Base. The Chief of JUSMAG-PHIL strongly recommends the speedy approval and fulfillment of the request. A similar request is made by Philippine President Ferdinand E. Marcos to the US Ambassador, William McCormick Blair, Jr., who also agrees that the US should furnish the requested items.

Only three of the remaining seven firms are awarded GLAD contracts: AAI, Aerojet, and Philco-Ford Aeronutronic Division. Each of the contract winners offers a different approach. AAI’s single shot prototype is a forward opening, pump action design. Aerojet submits a bulky SPIW-type semi-automatic launcher. Philco-Ford offers a single shot launcher with a barrel that swings open to either side. Significant by its absence in the contract award is Colt, who has by this point delivered 27,400 XM148.

AAI begins in-house trials in support of their SPIW improvement program. Real progress has been made in extending functional reliability. However, the pre-existing issue of rapid heating as surfaced with actual occurrences of cartridge cook-offs. Ironically, the prototypes had never managed to function long enough to experience this problem in the past.

Colt makes a connection between gas tube fouling and calcium carbonate levels in WC846.

After strong recommendations on the part of General Westmoreland, an accelerated schedule of M16A1 shipments to the South Vietnamese military is approved.

The Ichord Subcommittee releases its 51-page report, plus a 600-page hearing transcript. The US Army and Department of Defense (DOD) are faulted on a total of 31 points. Some of the primary criticism include the use of ball powder, hinting that Olin Mathieson’s WC846 was given contract preference over DuPont’s IMR powders, misinterpreting Olin’s “sole source” status. (Olin owns the rights to “ball powder.” However, Olin was not the Army’s only source of gunpowder. It just so happened that no one else managed to develop an alternate powder that would reliably meet the velocity/chamber pressure spec for M193.) In addition, Army sponsored modifications are blamed for malfunctions, delays, and cost increases. This includes the introduction of new buffers and the recent decision to chrome plate chambers. The effects of OSD interference are not mentioned.

McNamara sends a memo to Secretary Resor titled “Evaluation and Survey of the M16 Rifle.”

DDR&E John S. Foster, Jr. reports on a technical evaluation of the M16A1. It finds that the new buffer is a marked improvement and satisfactory with either WC846 or IMR. Malfunction rates are now approximately equal to the M14.

Colt submits 18 RTA to modify drawings for the stated purpose of improving dimensional control and depicting the parts as they are actually being produced.

COL Isaacs requests that WECOM‘s Quality Assurance Directorate provide overall quality assurance support with respect to the M16A1 Rifle Program. This represents a basic change since, prior to that time the WECOM QA Directorate furnished QA support to the PMR only as requested on a case-by-case basis.

An analysis of the criteria established for contractor periodic reliability testing (SAPD 235B) of the M16A1 rifle is initiated to determine whether these requirements should be continued or modified to conform to current small arms knowledge, technology, etc. The study includes all aspects of the program to determine numbers and types of allowable malfunctions and unserviceable parts, appropriate sample sizes, and testing procedures.

Out of 25 firms invited, twenty attend a pre-solicitation conference for M16/XM177 second sourcing. Only nine make the $1,000 bid deposit to receive a copy of the TDP and two M16A1 rifles.

Although he believes that the current Philippine inventory of small arms are adequate for their needs, CINCPAC Admiral Sharp recommends to the JCS that 200 M16 rifles from the September production be allocated to the Philippines. In his view, the expenditure of $35,000 in MAP funds will have a favorable political impact far out of proportion to the amount spent. The Secretary of the Air Force Harold Brown suggests that the 200 M16 rifles can be loaned from USAF stocks at Clark AB. The State Department refuses the request on the basis that first priority for the limited production of the M16 should remain with Vietnam-associated forces. Ambassador Blair appeals the denial as does Admiral Sharp.

Colt’s Robert Roy receives US Patent #3,348,328 titled “Adjustable Buttstock Assembly.”

Aberdeen’s BRL publishes “The Lethality of a Bullet as a Function of its Geometry.” From a set of formulae, the author concludes that the M193 projectile could be made to yaw more readily if the cylindrical section behind the cannelure were shortened.

Frankford Arsenal publishes “Quality Assurance Review of 5.56mm, M193 Ball Ammunition.”

Frankford Arsenal publishes the report “Metallurgical Analysis of 5.56MM Bullet, Copper Plated-Lead Cored.” Samples of 5.56mm bullets, copper coated and lead cored, representing two production lots (lots A and B), were analyzed. The purpose of the analysis was to ascertain metallurgical properties and characteristics of each lot which relate to quality and possibly to method of manufacture. The testing procedures included chemical, metallographical, electron micro-probe, and hardness analyses. The results indicated that the electroplating quality of Lot B was superior to that of Lot A, especially with respect to adhesion and strength of coating. The electroplating techniques used in the manufacture of each lot were different as evidenced by Lot A having one continuous layer of copper and Lot B having a banded structure of three distinct layers of copper.

Aberdeen’s D&PS releases “Engineer Design Test of Magazine, 20-Round, Disposable, For M16A1 (XM16E1) Rifle.”

On behalf of the US Army, Stanley Silsby receives US Patent #3,345,771 titled “High Capacity Magazine and Cooperating Firearm Structure.”

CDCEC publishes “XM148 Grenade Launcher Report With Addendum.”

D&PS sends a letter titled “Safety Evaluation and Feasibility Study of Attachment and Firing of Grenade Launcher, XM148 on Submachine Gun, XM177E2” to TECOM. Testing has confirmed the technical feasibility of firing the XM148 grenade launcher while attached to the XM177E2, and such firings can be considered safe from hand-held and shoulder positions. However, due to the configuration of the launcher sight, and its proximity to the shooter’s face, there is a possibility of injury from the sight when the XM148 is fired from an underarm support position. In addition, no firings should be attempted from the shoulder or underarm position with the buttstock in a forward position. The buttstock must be firmly latched open lest the recoil collapse the stock and drive the XM148 sight or any other protrusion of the XM177E2 into the shooter’s face. Eye protection is considered essential. Until a more comprehensive firing Evaluation has been conducted, it is recommended that the launcher not be fired with the XM177E2 loaded nor vice versa.

McNamara announces his pending resignation as Secretary of Defense.

General Johnson orders an “intensive review” of Army management practices related to M16 product improvements. The DOD‘s Weapons System Evaluation Group (WSEG) with the assistance of the Army-funded Institute for Defense Analyses (IDA) prepares for yet another operational trial of the M16.

The M16 Rifle Review Panel convenes in the Weapon Systems Analysis Directorate of the OCSA.

As a result of complaints received from the USMC and other users, a program is conducted to provide a monthly quality audit of M16A1 rifles and repair parts representative of production on Colt’s current production contract. Rifles and components are selected monthly from accepted items on the contract and shipped to a Government Arsenal for a quality audit to determine conformance to contract requirements.

A new QALI is issued to DCASD-Hartford, requesting that the Government representative perform certain mandatory inspections (Product Inspection Type A – PIT A) considered necessary to determine conformance to contract requirements prior to the acceptance of rifles. The letter further requests that periodic reports containing results of contractor’s monthly performance testing and final examination of rifles be provided for utilization in the analysis of data and preparation of the monthly M16A1 rifle product assessment report.

A program is established for obtaining information concerning malfunctions encountered with the M16A1 rifle during Vietnam-oriented training at CONUS training stations. This is accomplished by visits of a team of quality assurance personnel who gather data on-site and provide appropriate recommendations relative to utilization of the data. These actions will be accomplished in connection with the basic infantry training conducted at Fort Polk, Fort McClellan, and Fort Jackson.

The “M16A1 Rifle System Test Coordinating Team” is established at Frankford Arsenal. Its job is to investigate ammunition performance and its relationship to M16 rifle function.

CDCEC publishes “Report on the Reliability of the M16A1 Rifle During Phase I of IRUS 70-75 Field Experimentation.”

The US State Department defends its refusal of M16 for the Philippine Constabulary. Philippine Under Secretary of Defense Syquio make a strong personal appeal for the rifles stating that the PC need the rifles as the Huk already have them. The US Embassy forwards the argument that the Huk unrest could lead to a Communist insurgency, and must be stamped out quickly. So far President Marcos has been unwilling to take decisive action, and the delivery of the rifles could be used as leverage to encourage such actions.

MUCOM suspends use of M196 Tracer Lot LC-12081 for anything but emergency combat use. This is due to bullet jacket breakup. The ammunition lot is loaded with WC846.

While on a visit to Aberdeen, Frankford Arsenal representatives are told of the poor performance of M196 Tracer with the XM177E2.

Colt’s Kanemitsu (Koni) Ito files a patent application for a magazine dimension “Go-No Go” field gauge.

Colt’s George Curtis and Henry Tatro begin work on the CMG-2.

CDCEC also publishes “XM148/M79 Basis of Issue Experiment Report.”

AAI begins a second set of in-house SPIW trials now concentrating on eliminating the cook-off problem.

US Army Theater Distribution of M16 Rifle

Theater Total on Hand 31 DEC 67
Vietnam 191,354
USARPAC Less Vietnam 9,053
Other Overseas 1,947
STRAF 32,802
CONUS less STRAF 30,340
Total Active Army 266,904
Reserve Components 1,151
CONUS Depot 7,438
Total Worldwide 275,493

A two-week quality verification visit is conducted at Colt by a team of two quality assurance specialists to assess the overall adequacy of product inspection, inspection equipment, and the quality assurance program.

SAPD 253B is amended for the second time. It now requires 100 percent testing of the rifles for function firing, targeting and accuracy, headspace and trigger pull. Each barrel assembly and bolt is subjected to a high-pressure test with subsequent magnetic particle inspection. On a sampling basis, rifles are tested for firing pin indent, interchangeability, cyclic rate and reliability. In addition, each rifle is subjected to a manual and visual examination.

AMC issues “Rifle 5.56mm M16: Queries on Grenade Launcher Attachment and the Powder.”

Aberdeen publishes “Letter Report of the Initial Production Test of Chrome Plated Chambers for M16A1 Rifles.”

OACSFOR publishes another draft of the ARSAP.

A central point of contact is established in the ODCSLOG, to monitor and control funding, procurement, modification, distribution, and maintenance of the M16A1.

Three additional firms place bid deposits for the M16 TDP, while four of the original bidders withdraw.

US Charge d’Affaires Wilson tells Philippine President Marcos that delivery of the rifles is contingent upon taking decisive action against the Huk. Marcos agrees to further US conditions that the M16 be on loan and that no publicity about this agreement be made. Upon receiving Marcos’ assurances, the State Department approves the loan of 200 M16 and 90,000 rounds of ammunition from USAF stocks at Clark AB.

The Department of the Army and the Commander in Chief, US Army Pacific (CINCUSARPAC) agree to release 2,320 M16A1 to Thailand for training purposes. MACV commander General Westmoreland and the MACTHAI commander coordinate plans to provide the remainder of the 4,943 M16 rifles required by the Thai Army division deployed to Vietnam.

Aberdeen’s BRL issues the report “Effectiveness Comparison of 1:12 and 1:14 Inch Twist Rates for M16A1 Rifle.”

Frankford Arsenal releases the report “Fouling Test Investigation of 5.56MM Ammunition/Weapon System.”

WC846 is withdrawn for use in loading M196 tracer cartridges. WC846 is replaced by DuPont’s IMR 8208M (formerly EX 8208-4).

Stephen A. Doilney, Chief of Aberdeen’s Small Arms & Aircraft Weapons Branch, sends a message to WECOM titled “Firing of M196 Cartridges in XM177E2 Submachine Gun.” Doilney states that testing has shown excessive yaw and dispersion with the M196 Tracer. There is serious concern that the incompatibility of M196 Tracers with the XM177E2 cannot be solved by changes in ammunition only. Total compatibility may require redesign of the XM177E2 muzzle device.

IWK‘s Ludwig Six and Rudolf Niemann file an US patent application for the design of a heavyweight 5.56mm projectile.

CETME‘s Dr. Günther Voss receives US Patent #3,357,357 titled “Rifle Bullet.”

Colt’s Henry Into files a patent application for the design of the CGL-5 grenade launcher.

William C. Davis sends a memo to COL Isaacs titled “Redirection of SPIW Program to Caseless Ammunition.”

(Next: 5.56mm 1968)

by Daniel E. Watters, Small Arms Historian
Post questions or comments at The 5.56mm Timeline’s Facebook page.

Document History
Publication: 12/10/1998
Last Revised: 05/17/2009
Author’s Note
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.

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