The 5.56 X 45mm “Timeline” – 1966

A Chronology of Development by Daniel E. Watters



FN introduces the 5.56mm CAL.

Spain’s CETME begins studies for a 5.56mm rifle design.

Brazil tests the AR-18.

Foster Sturtevant retires from Colt.

Lake City Army Ammunition Plant begins production of the M196 Tracer.

Federal begins to offer a 68 grain 5.56mm Ball cartridge.

General Electric designs a tungsten core 5.56mm AP bullet for ArmaLite. FN also produces a tungsten core AP projectile; the cartridge is later designated the P96.

Early 1966:
WECOM Commanding General MG Roland B. Anderson requests transfer to WECOM of responsibility for licensing rights negotiations. Anderson orders LTC Yount to draw up an unilateral plan to establish a second source of production for the M16/XM16E1.

Army Theater Distribution of M16 Rifle

Theater Total on Hand 1 Jan 66
Vietnam 32,068
USARPAC Less Vietnam 481
Other Overseas 1,722
STRAF 23,156
CONUS less STRAF 2,514
Total Active Army 61,349
Reserve Components 1,197
CONUS Depot 19,264
Total Worldwide 81,810


Because of the increased requirement for the M16 rifle and the need for an expanded production base, OASD(I&L) proposes two alternatives. The first is to increase Colt’s production to the 25,000 monthly rate as rapidly as possible. The second is to establish a second source of production. It is estimated, however, that it will be 22 months before the first delivery can be made from a second source, since no military technical data package exists. The Army advises Colt that an order of approximately 400,000 rifles is forthcoming.

DCSLOG LTG Lincoln revises his projection for necessary 5.56mm ammunition production from 100 million a month to 150 million rounds per month. In a memo titled “Expansion of Production Capacity for 5.56mm Ammunition at Lake City and Twin Cities,” ASA(I&L) Dr. Brooks revises funding required for production line conversions at Lake City and Twin Cities.

Ammunition Production Expansion

Facility Previously Approved Revised to 5.56mm Capacity per Month
Lake City AAP $2,000,000 $1,621,000 40,000,000
Twin Cities AAP $3,500,000 $4,300.000 100,000,000
Total $5,500,000 $5,921,000 140,000,000


Badger Army Ammunition Plant is reactivated. Olin had operated Badger AAP for the Army since 1951, but it had been in stand-by status since 1958. Days later, the labor strike at Olin’s East Alton plant ends.

The TCC notes that the XM16E1’s malfunction rate in testing is not serious enough to interfere with combat operations in the field, but it is enough to warrant corrective action.

Colt presents the TCC with Foster Sturtevant’s latest development, an improved buffer assembly with multiple internal sliding weights. While intended primarily to prevent light strike misfires due to bolt bounce in automatic fire, Sturtevant’s new buffer unwittingly saves the day on a second front. Since the new buffer weighs roughly three times more than Stoner’s original design, it reduces the overall cyclic rate to acceptable levels. The difference in reliability had already been seen in SAWS testing between the XM16E1 with the old buffer and the CAR-15 HBAR with the new buffer. The latter had 3.02 stoppages per 1,000 rounds compared with 11.15 stoppages per 1,000 rounds for the XM16E1. The TCC assigns the further test and evaluation of Colt’s new buffers to Springfield Armory.

Colt also offers improved handguards, handguard slip ring, and cadmium plated slip ring spring.

The US Army initiates work on incorporating center index zero on rear sight and upper receiver.

Frankford Arsenal reports to the TCC on their tests of the previous month, which indicated a higher cyclic rate for the M16 rifle with WC846 ammunition than with CR 8136 ammunition. By now, 12,000 rounds had been fired in each of four XM16E1 and two AR-15, utilizing the original design buffer.

ACSFOR LTG Conway transmits the letter “Procedures for Expediting Non-Standard, Urgent Requirements for Equipment (ENSURE).” It gives the authority and establishes procedures for directly forwarding to ACSFOR new materiel requirements for use by the US Army in the South Vietnam.

The US Army awards a $16,650 contract modification to Colt for 150 M16.

Procurement is authorized for 2,050 CAR-15 “Submachine guns.”

The CDC establishes a requirement for 30 round magazines. Ideally, all future production M16-type rifles will come equipped with these. However, Colt has difficulties with their first few designs. Made with a continuous curve, the magazines would not fit properly in some magazine wells given the machining tolerances in the lower receiver. (The current straight-then-curved 30 round magazine design will not be ready for production until late 1968/early 1969.)

Springfield Armory publishes the report “Barrel Erosion Study of Rifles, 5.56MM, M16 and XM16E1–A Joint Army-Air Force Test.” Twelve XM16E1 rifles were fired to the end of their barrel bore service life. Measurements of the barrel bore were taken periodically with an air gauge, and an expanding mandrel gauge. It was determined that the maximum acceptable barrel bore diameter would be 0.2206 in. The barrel bore was considered serviceable for either overseas or CONUS use if that diameter had not advanced forward of the origin of the rifling further than 3.625 inches. Advancement to 6.625 in. was considered the cut-off for CONUS use only, and advancement beyond 6.625 would constitute complete rejection of the barrel. Gage, Barrel Erosion C7799792, designed by Springfield Armory, is recommended for this purpose.

TECOM publishes “Analysis of Results of SAWS Engineering and Service Test.”

Colt requests permission to begin shot peening the bolt to increase its life span.

A SPIW Design Approval and pre-In-Process Review Meeting is held at Aberdeen.

The first sample of contractor-fabricated XM216 ammunition with the thicker walled primer cups is received. Leaky primers and punch-outs are experienced.

Due to the breakage of hammers and the splitting of muzzle devices in testing, a meeting is held at WECOM HQ to discuss the Springfield SPIW‘s status. Frankford Arsenal and Springfield are to prepare position papers on the technical advantages and a cost estimate for a program slippage of 90 days. This is to be expedited to allow for preparation of the AMC‘s position paper for the formal SPIW In-Process Review Meeting scheduled for February.

On behalf of the US Army, Stanley Silsby files a patent application for the side-by-side magazine of Springfield Armory’s 2nd Gen. SPIW.

M16 training is expanded for all US Army units and replacements deploying to Vietnam.

AMC General Counsel Barnes submits proposals to Colt President Benke for licensing agreement. Benke replies to Barnes proposing a $5,000,000 lump sum payment and a 5.5 percent royalty.

LTC Yount proposes awarding the M16/XM16E1 second source contract to one of the former M14 manufacturers. However, Yount states that a second source’s production is not likely to start for at lest 13 months after the award is made.

In a memo titled “Procurement of Rifles, 5.56mm, M16, and XM16E1,” the OASD notes the OSD decision to expand Colt’s production to 25,000 rifles per month. Colt is notified to prepare accordingly. Colt is also led to believe that the order of additional rifles will be added to the current contract.

WECOM‘s Quality Assurance Representative (QAR) reports that Colt’s Quality Control Program is generally satisfactory at that time.

The Army Chief of Research and Development, LTG Dick testifies to the House Armed Services Committee that the Army has submitted a proposal to Colt for obtaining M16 manufacturing rights.

ACSFOR LTG Conway approves request for expediting fielding of CAR-15 “submachine guns” to USARV as possible replacement for selected pistols and submachine guns currently in service.

The requirement for the Colt CAR-15 “Commando” is increased by 765.

USARV requests priority airlift of cleaning rods, and voices an urgent need for a chamber cleaning brush.

Research at Lackland AFB confirms Colt’s claim of increased parts life for shot peened bolts.

Rock Island conducts tests comparing relative merits of Dri-Slide versus the current issue small arms lubricant VV-L-800. Ultimately, the Army concludes that VV-L-800 is superior to Dri-Slide.

The ammunition specifications are changed to eliminate calcium silicide as an acceptable primer compound because its use contributes to excessive carbon fouling.

Frankford Arsenal publishes “Test of Cartridge, 5.56mm Ball, M193, Lots RA 5074 and WCC 6089 in Rifles, 5.56mm, XM16E1, and AR-15.” It reports that the ammunition lot loaded with WC846 gave lower chamber pressures, higher port pressures, a higher cyclic rate, a greater malfunction rate, greater fouling, more variation in velocity due to variations in handling, and less bore erosion than did the ammunition lot loaded with CR 8136.

Colt’s Foster Sturtevant receives US Patent #3,236,155 titled “Firearm Having an Auxiliary Bolt Closure Mechanism.”

LTC Yount informs Edward C. Herkner that his ruptured cartridge case extractors worked perfectly. However, they are now having difficulty tracking the origin of the request for the extractors.

Gene Stoner receives US Patent #3,235,997 titled “Bipod Gun Mount.”

WECOM conducts the formal In-Process Review of the SPIW program. Neither AAI nor Springfield Armory have their second-generation SPIW prototypes ready. Indeed, some items have not even been designed, much less manufactured. A 90 day waiver for delivery is given as a result.

On behalf of the US Army, Robert F. Magardo receives US Patent #3,235,993 titled “Ejector-Extractor Mechanism for Repeating Auxiliary Firearm of Pump Action Type.”

The US State Department’s Office of Munitions Control authorizes ArmaLite to enter a co-production agreement for the AR-18 with Howa in Japan.

Frankford Arsenal issues the report “An Effectiveness Analysis of Spin-Stabilized Rifle Systems Based on a Caliber .17 Projectile.”

McNamara testifies before the House Armed Services Committee. He is asked about whether a second source for M16 production is required in light of the recent strike at Olin’s East Alton plant. McNamara indicates that licensing is being negotiated with Colt, and Colt is being cooperative.

The US Army informs Colt that the forthcoming order of ~400,000 rifles will be part of a new contract.

The TCC discusses problems with the XM16E1’s rate of fire during testing.

Frankford Arsenal is instructed to continue investigating problems caused by ball powder. They are also to determine what changes need to be made to the ammunition purchase description to define acceptable performance with ball powder and IMR.

Badger AAP resumes production of Ball Powder. They had previously produced it during the 1950s.

D&PS publishes the Volume I and II Final Reports for “Engineering Test of Small Arms Weapons Systems (SAWS).”

The British Ministry of Defence (MOD) tests the ArmaLite AR-18. It is found to be fairly sensitive to sand and mud.

Cadillac Gage introduces a series of product improvements to the Stoner 63. The updated weapon is now known as the Stoner 63A.

Colt’s Robert Roy files a patent application for the design of the CMG-1.

Springfield is advised to proceed as if a 90 day slippage is in effect. Springfield immediately begins updating of its SPIW development weapons.

Frankford hurries to deliver a 2,000 round sample of XM216 ammunition with a second increase in primer cup wall thickness. The ammunition modification along with a modification to the Springfield SPIW‘s firing system eliminates primer punch-outs. Unrestricted development testing is now possible.

However, the alternate point weapon feed system contract is terminated because of the contractor’s increased costs, Springfield’s inability to keep the contractor supplied with an updated weapon, and a lack of supply of suitable ammunition for development.

Olin-Winchester’s James H. Johnson, Arnold L. Fowler, Julius E. Brooks, and Harvey H. Friend file a patent application for the lockwork of the Winchester SPIW and grenade launcher.

LTC Yount is promoted to Colonel.

The USMC Quartermaster General initiates procurement of the XM16E1.

The US Army awards $14,500 to Colt for altering 2,840 M16.

An updated version of the M16/XM16E1’s performance specifications is approved as SAPD 253B “Acceptance Testing Specification for Rifles, 5.56mm M16/XM16E1.”

AMC General Counsel Barnes writes Colt President Benke asking for comments on a draft license agreement. Barnes indicates that WECOM would like to see a license agreement in place before the new letter contract is finalized. Benke replies to Barnes indicating several problems with the proposed licensing agreement: 1) No payment for the TDP; 2) Includes rights for the XM148 for which Colt wishes to negotiate separately; 3) Ceilings on royalties; and 4) No provision for maintaining minimum production base at Colt.

USARV publishes “Evaluation of US Army Combat Operations in Vietnam,” ARCOV for short. The study is an evaluation of the four types of maneuver battalions operating in Vietnam. It recommends changes in doctrine, materiel, and organization to increase the combat effectiveness of the maneuver battalions. Amongst its findings are that the characteristics of the XM16E1 make it well suited for the rifleman in Vietnam. The light weight of the weapon and ammunition increases the mobility of the soldier and adds to his firepower since he can carry more ammunition. The automatic feature is desirable at the time of an initial attack or ambush and is effective at all ranges on area targets, which represent 76 percent of all targets. The frequency of situations where the automatic feature is need outweigh those where it is not required. All units still equipped with the M14 and M14A2 who were surveyed agreed that the substitution of the XM16E1 would increase the firepower of the squad and decrease the rifleman’s load. In addition, it was established that the M1911A1 pistol was an inadequate individual weapon for the M79 grenadier, but there was no consensus as to what should replace it other than that it should have offensive potential. Suggestions included replacing the M1911A1 with the XM16E1 or a M16-based carbine, or the replacement of both the pistol and grenade launcher with a dual purpose weapon like the XM16E1/XM148. Either change is estimated to add 25 percent to the firepower of the rifle squad. The authors recommend that all maneuver battalion riflemen be equipped with the XM16E1, and that the XM16E1 replace the M1911A1. A dual purpose weapon should be developed for the grenadier, such as the XM16E1/XM148 combination. In his transmittal letter, General Westmoreland recommends that the proposed replacement of the M1911A1 with the XM16E1 be coordinated with an planned USARV evaluation of 2,815 CAR-15 submachine guns.

The CDC publishes “Combat Developments Study Directive, Infantry Rifle Unit Study, 1967-1975 (IRUS-75).” IRUS-75 is to examine the ideal size, composition, and equipment of infantry and mechanized infantry rifle platoons and squads.

The TCC approves the use of EX 8208-4 powder.

In a document titled “Improved Performance of Ammunition for the M16 Rifle,” Gerald A. Gustafson recommends that the 68 grain .224″ homologue to the .30 M1 Ball be revived for use in the 5.56mm cartridge. Gustafson suggests that 50,000 bullets of this design be purchased from Sierra for constructing test ammunition. He also recommends using test rifles with both 1-in-12″ and 1-in-9″ twist barrels. (At the time, Gustafson is assigned to Aberdeen’s Test Analysis and Operations Office.)

Colt’s Foster Sturtevant files a patent application for his improved buffer assembly.

Springfield begins testing of the new buffer.

During testing at CDCEC, a XM16E1 suffers a casehead rupture with a cartridge from Federal Cartridge lot FC1830. Use of Lot FC1830 is suspended until MUCOM can investigate.

The BRL publishes “SAWS Effectiveness Data.”

CDEC-TB issues a letter titled “Essential Elements of Analysis (EEA), Small Arms Weapons System (SAWS) Program.”

Colt submits RTA to increase the tension of the bolt catch spring. This is in response to premature bolt catch engagement experienced during the SAWS trials at Fort Ord.

Arthur Miller files a patent application for the design of the AR-18’s folding stock and its lock mechanism. Miller also receives US Patent #3,246,567 titled “Operating Rod for a Self-Loading Firearm.”

Winchester delivers 10 SPIW grenade launchers, which prove to be functionally unsatisfactory. A contract supplement is placed for the functional improvement of the launcher with delivery scheduled early in July.

The US Army updates its FY 1966 budget requirement for M16 rifles as follows:

US Army
Original Submission 30,134
USARV 68,000
In lieu of M14 rifles, plus consumption 115,271
South Vietnam Army 100,000
ROK Army 14,000
Total Army Procurement 327,405
Other Customers
US Air Force 60,082
US Marine Corps 91,872
US Navy 2,000
US Coast Guard 1,411
Total Other Customers 155,365
Grand Total 482,770


McNamara testifies before the House Armed Services Committee. He states that the sole-source procurement of M16 from Colt will result in faster deliveries than attempting to create a second-source.

At a meeting with Secretary Ignatius, Colt President Benke agrees to negotiate TDP and license rights in good faith.

In communications with AMC General Counsel Barnes, Colt President Benke expresses great interest in the US Army’s future requirements for the XM16E1.

Production of 5.56mm ammunition using EX 8208-4 begins.

Springfield Armory concludes testing of the new buffer and publishes “Evaluation of Proposed Buffer Designs.” It reports that the M16 with the new buffer and WC846 does not perform as well as the old buffer and CR 8136.

TECOM publishes “Engineer Design Test of Cartridge, 5.56mm, Ball, M193 (Evaluation of Improved and/or Alternate Propellants).”

After testing, the USMC recommends Dri-Slide as suitable for Marine use. The Marine evaluators were aware of the Army’s earlier negative assessment, and found fault with WECOM‘s testing.

The BRL publishes “Small Arms Weapons Systems (SAWS) Effectiveness Data.”

CDCEC publishes the report “Small Arms Weapon Systems (SAWS).” Field experimentation was conducted to determine the relative effectiveness of rifle and machinegun squads armed with US 7.62mm, Soviet 7.62mm, Colt 5.56mm, and Stoner 5.56mm weapons. This report describes the experiment, the effectiveness measures used, the results, and the conclusions. Results are concerned with training, materiel reliability, and the fire effectiveness of squads armed with the different weapons and firing both simplex and duplex ball ammunition. Measures of effectiveness were the level of target effects and the ability of the weapons to sustain the effects. Data includes the number of targets hit, total number of hits on targets, number of near misses as an indication of suppressive effects, and the amount of ammunition expended–all as a function of time. Squad size, organization, and weapon system weight were held constant. Squads armed with low impulse 5.56mm weapons were superior to squads armed with 7.62mm weapons in target effects, sustainability of effects, and overall effectiveness. Duplex ball ammunition was generally superior to simplex ball ammunition at close ranges. Data related to lethality was published in a separate classified annex. However, results indicate the superiority of 5.56mm weapons.

After testing, Frankford Arsenal clears Federal Cartridge lot FC1830 for use.

Colt’s Robert Roy files a patent application for an improved collapsible buttstock.

Colt submits RTA for the charging handle latch and its spring. This is in response to premature unlatching of the charging handle experienced during the SAWS trials at Fort Ord.

USARV submits ENSURE #77 for XM16E1 “silencers.”

A contract is finally awarded for the procurement of cleaning brushes.

Contract DAAF03-66-C-0018 is signed with Colt for 403,905 XM16E1 rifles worth $45,035,407.50. The US Army will receive 213,405. Another 114,000 are earmarked for military assistance for the South Vietnamese, and the final 76,500 will go to the USMC. The contract will be amended 256 times before it is complete. One of the first comes less than a week later for an additional 15,372 rifles for the USMC and 2,000 M16 worth $1,835,804. The contract ultimately acquires a grand total of 808,230 XM16E1/M16A1 and 28,580 M16. A provision is incorporated into the contract that the Army and Colt agree to negotiate in good faith to allow the Government to obtain an irrevocable, nonexclusive license to manufacture the M16. Negotiations are to be completed on or before December 1, 1966.

Separate contracts for 2,815 Colt Commandos and 19,236 XM148 grenade launchers are also signed.

Sufficient M16 are made available to all US Army personnel armed with the M14 in divisional maneuver elements, separate infantry battalions and brigades, and armored cavalry regiments deploying to Vietnam.

Singapore broaches the subject of acquiring 15,000 to 23,000 AR-15 rifles. The US State Department’s Office of Munitions Control consults with the DOD, which does not object to the sale.

AMC General Counsel Barnes again writes Colt President Benke announcing that WECOM has asked that Barnes’ office resume responsibility for licensing agreement negotiations. Barnes indicates that negotiations will not be possible on the basis of known future requirements, other than the relatively insignificant USAF requirement over the next five years.

CDC submits the report “Army Small Arms Weapons Systems Study.” It is based on information gathered by the CDC‘s Infantry Agency and Combat Arms Group.

CDC also publishes “Army Small Arms Weapons Systems Study (SAWS) Troop Training Test.”

CDCIA publishes “SAWS Troop Acceptability Test.”

Booz-Allen Applied Research, Inc. publishes “Small Arms Weapons Systems (SAWS) Computer Simulation” and “Small Arms Weapons Systems (SAWS) Troop Test Program.” The former evaluates the Springfield Armory and AAI SPIW and Universal Machine Gun (UMG) systems; the 13mm and 20mm Gyrojet systems; the Avco AVROC 5-20, 8-20, and 25-40 systems (rocket boosted grenade cartridges); and parametrically designed 0.65 lb-sec, 1.2 lb-sec, and 2.6 lb-sec impulse weapon systems.

TECOM also submits its SAWS report. It notes that the low level of reliability of the XM16E1 rifle is not considered to be representative of the rifle’s performance. Instead, it indicates the need for improvement in manufacturing quality control and the investigation of the effect of the ammunition on weapon function.

M193 and M196 cartridges loaded with DuPont EX 8208-4 begin to arrive for issue.

The US Army orders 997,410 pounds of EX 8208-4 for loading 5.56mm ammunition at government ammunition plants.

During the Infantry Rifle Unit Study (IRUS) at CDCEC, another XM16E1 suffers a casehead rupture with a cartridge from Federal Cartridge lot FC1830. The rifle is extensively damaged. This is the third incident of casehead failure recorded during the history of the M16/XM16E1 program. William C. Davis is sent to investigate. Upon examination, Davis requests a representative be sent from MUCOM. Testing by Frankford Arsenal and Federal Cartridge reveal no problems with Lot FC1830; however, case hardness tolerances are suspected. Despite ~230,000 other rounds having been fired without problems, Lot FC1830 is withdrawn and scrapped. Use of the follow-on Lot FC1831 is suspended as a precaution.

Frankford Arsenal finalizes drawings for the XM195 grenade cartridge. The military specification is not issued for another two months.

Aberdeen’s BRL releases the report “The Aerodynamic Properties of a Caliber .223 Remington Bullet used in M16 (AR-15) Rifle.”

Frankford Arsenal publishes “Tracer Projectile for SPIW Point Target Ammunition.”

Dunlap and Associates, Inc. submits “Human Factors Engineering for the Special Purpose Individual Weapon (SPIW) Launcher” to Olin-Winchester.

The US Army approves the introduction of the new buffer.

A casehead rupture damages a fourth rifle, this time with Remington ammo (Lot RA5189).

2,753 XM16E1 are shipped to Fort Polk.

MACV approves the delivery of 630 XM16E1 rifles to the Philippine Civic Action Group, Vietnam.

Aberdeen’s BRL issues the report “Effectiveness of Small Arms Weapons Systems (SAWS).”

ACSFOR LTG James H. Polk sends a memo to General Johnson titled “Long-Range Program for Army Small Arms.”

Colt requests and receives waiver on 500 XM16E1 with illegible lower receiver markings.

Colt denies a WECOM request for the use of magazine drawings to support development of disposable magazines. In return, WECOM considers reverse engineering the dimensions from existing magazines and rifles.

The PMR Office publishes “Special Purpose Individual Weapon Newsletter Number 5.”

Springfield Armory releases POMM 1005-251-12 “Special Purpose Individual Weapon (SPIW) – Preliminary Operating and Maintenance Manual.”

Olin-Winchester publishes the report “Olin SPIW Launcher” outlining the development of their grenade launcher design.

Springfield Armory publishes the report “Investment Cast Components for SPIW.” An investigation was conducted to determine the feasibility of using investment cast components for the Special Purpose Infantry Weapon (SPIW). Suitably shaped components for the process were investment-cast, machined, and heat-treated for service tests. Results of these tests show that the service life of the cast components is equal to, or superior to, that of the wrought components. Investment casting is an efficient and economical method of fabricating the selected components.

All US Army maneuver (combat arms) units in Vietnam have been issued the XM16E1. Some support units do not transition from the M14 until several years later.

500 XM16E1 are shipped to III MAF.

Aberdeen’s HEL publishes “Small Arms Use in Vietnam: Preliminary Results.” The HEL developed a questionnaire to find out how small arms are used in Viet Nam. This report gives preliminary results from a sample of 121 combat troops.

The CDC releases its final conclusions of the SAWS study. The CDCIA developed its study recommendations by placing primary reliance on the CARO computer simulation, the assumed availability of SPIW in 1970, the 1965 Army Materiel Plan (AMP) assets-requirements balance, and a concept of “selective modernization.” The policy of selective modernization envisages replacing one-third of the total small arms inventory every seven years, with priority for allocation of new weapons going to combat maneuver units. The principal CDCIA recommendations of the SAWS Study are:

  1. Procure no additional rifles beyond those XM16E1 rifles currently on order until SPIW becomes available in 1970;
  2. Initiate a program of selective modernization by procuring SPIW, when available, in sufficient quantities to replace rifles, automatic rifles, and grenade launchers for infantry maneuver units only (approximately 192,000);
  3. Retain the M60 as the future infantry machine gun until the Universal Machine Gun (UMG) is developed, about 1972;
  4. Improve the effectiveness of SPIW in the automatic rifle role or adopt the UMG with a bipod mount to this role;
  5. Continue development of the UMG to make it at least as effective as the M60, while preserving the weight-savings of the current conceptual UMG design, and then in 1972, replace all machine guns with the UMG;
  6. Initiate and fund a vigorous research and development program for the purpose of: a) developing caseless ammunition by 1976 with improved projectiles for use in a redesigned SPIW with a further improved area fire capability; and b) discovering or developing a new lethal mechanism permitting design of radically different small arms systems; and
  7. In 1976, continue the program of selective modernization by procuring 500,000 SPIW redesigned to utilize caseless ammunition. About half of these will have the area fire capability and half will not.

The secondary recommendations of the SAWS Study are:

  1. Develop a method of measuring in actual test firing the combat effectiveness of platoon weapon mixes. In particular, assess the interrelations between different types of weapons in a conventional mix and assess the value of fragmenting rounds in comparison with conventional ball projectiles;
  2. Establish a program to develop a comprehensive and detailed computer simulation models for evaluation than was possible with the computer model used in the current study;
  3. Procure and issue 7.62mm duplex ammunition to complement the M80 cartridges already in the inventory;
  4. Reduce the cost of small arms ammunition of current and conceptual systems; and
  5. Monitor rocket-type small arms systems continually to permit exploitation of any inherent military potential.

Behind these recommendations is the substantive conclusion that among weapons currently in the inventory the 5.56mm weapons are better for use in low intensity warfare, such as that encountered in Vietnam, whereas the 7.62mm weapons are more effective in high or mid-intensity warfare, such as that which would be encountered in Europe and Korea. This conclusion is mainly derived from the computer simulation.

The SAWS study is submitted to the Army Staff. In a letter to ACSFOR LTG Polk accompanying the study, the CDC modifies the CDCIA study recommendations in several instances:

  1. Rifle Procurement: An increase in stockage objectives or significant decrease in assets by combat loss or wear-out, requiring an additional buy of rifles before 1970, should be satisfied by purchase of XM16E1 weapons;
  2. Adoption of SPIW: The final decision to adopt and field SPIW must be contingent upon results of further experiments and tests. It is understood that some difficulty is being experienced in current SPIW comparative evaluation testing by the AMC. To be acceptable, SPIW should essentially equal the theoretical capabilities used in this study;
  3. Automatic Weapons: The need for an automatic weapon in the squad is recognized. This recommendation does not exclude from consideration weapons other than the UMG and SPIW; and
  4. General: While the 7.62mm systems do provide advantages over the 5.56mm systems against materiel targets, the intensity of conflict is not a sound basis for a clear choice between two weapons.

“An environmental distinction, giving due consideration to terrain, existing built-up areas, and estimated equipment resources of the enemy offers a better basis for choice. This minor advantage offered by the 7.62mm system does not, of itself, warrant the maintenance of two different small arms weapon systems in the inventory. It is the position of this command that the total SAWS Study does indicate that the 5.56mm rifle offers the most promise for improved capability for the money spent . . . the concept of selective modernization is an excellent idea whereby the Army takes deliberate advantage of progressive improvements in small arms. Every reasonable effort should be made to insure that Army units are equipped with the best possible weapons. To this end, the indicated timing must not become a constraint; advances in the state-of-the-art must be taken advantage of as they occur.”

Colt’s Robert Roy receives US Patent #3,267,601 titled “Adjustable Buttstock Assembly.”

WECOM publishes “Evaluation of Dri-Slide as a Lubricant for Small Arms Weapons.” Rock Island testing concludes that Dri-Slide is inferior to VV-L-800 in wear and corrosion resistance except in a sandy environment.

The USMC issues “Specific Operational Requirement, Individual Weapon” and “Specific Operational Requirement, Lightweight Individual Weapon.”

Materiel developed by Springfield Armory during engineering support of the M16/XM16E1 program is transferred to Rock Island Arsenal.

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

The military specification for the M232 Dummy Cartridge, MIL-D-60254(MU), is revised to MIL-D-60254A(MU).

In a informal briefing by COL Yount for the Commanding General of TECOM, the SPIW type classification objective is pushed back to June 1968.

The second-generation SPIW prototypes are submitted for testing. The Springfield Armory candidate required significant redesign from its original bullpup configuration. While the new design still meets the length restriction, it also remains overweight. The dual magazine design has been changed to a side-by-side plan constructed of clear Lexan. When one side runs dry, feed is automatically switched to the opposite side. The Winchester grenade launcher is fitted; however, it now uses a preloaded, disposable magazine. One thing that proves especially difficult is the US Army’s insistence that both weapons be fired from the same trigger. The complex linkages involved result in the grenade-trigger option having a 25 pound trigger pull.

AAI didn’t have quite as much work to convert their previous design. To met the “conventional stock” requirement, they design a clever one-piece polymer buttstock/rear sight housing/magazine well. AAI’s semi-automatic grenade launcher is finally ready, and uses a harmonica-style magazine. The magazine automatically ejects when empty. However, the overall weight still exceeds the project limit. (As an alternative, AAI proffers another grenade option, the DBCATA: Disposable Barrel and Cartridge Area Target Ammunition. The DBCATA allows the 40mm grenade to act as its own launcher. While it would lead to a major reduction in system weight, the DBCATA is considered to be prohibitively expensive. Essentially, you would be throwing a barrel away after each shot.)

Neither entry is terribly reliable, none achieve the weight goal, and the most of the pre-existing problems are still unsolved, including the various ammunition issues. (By this point, the XM110 and XM144 had been replaced by the 5.6x57mm XM645 and 5.6x44mm XM216 cartridges.) Observers state that the blast and flash signatures even exceed those of the unmodified Colt “Commando”.

The BRL publishes “A Kinematic & Dynamic Evaluation of the Universal Light Machine Gun, 5.56mm.”

Rock Island also publishes “Coordinated Test Program (CTP) for the Special Purpose Individual Weapon (SPIW).”

The British MOD tests an improved model of the AR-18. It still fails in sand and mud tests.

A shortage of M16 and M14 rifles results in the issue of M1 rifles to some units in the US.

Since March 1965, US forces in Vietnam have been consumed 99 million rounds of 5.56mm ammunition. Approximately 89 million of these cartridges were loaded with WC846, while the rest were loaded with CR 8136.

Colt submits first written offer on a licensing agreement: $9 million for the rifle alone (no XM177), 9 percent royalty, and $800,000 for reproduction of the TDP.

The US Army’s new systems analysis group, the Force Planning and Analysis Office (FPAO), begins studying the data collected during the SAWS trials. The civilian co-director of the FPAO, Dr. Jacob A. Stockfisch, is fresh from serving as the chief scientific advisor to CDCEC‘s portion of the SAWS trials. Stockfisch has little use for the computer simulations performed by CARO. Instead, perhaps not surprisingly, he concentrates on the data provided the CDCEC tests. In a memo to General Johnson, Stockfisch recommends that the SPIW be reoriented to a long-range research program, current procurement should center on the XM16E1 and the M60, with the possible adoption of the Stoner 63 to fill the Automatic Rifle role.

DCSLOG LTG Lincoln publishes the 1966 Army Materiel Plan. The new AMP implies that the SPIW has been selected as the successor system to the M14.

In a message to General Besson, the 1st Logistical Command requests the airlifting of 50,000 cleaning rods and 50,000 bore brushes to Vietnam as soon as possible.

The closed-end “birdcage” flash hider is approved to replace the open three-prong model. The latter was prone to snagging and breakage, and was also suspected in assisting the capillary movement of water into the bore.

Rock Island Arsenal releases the Preliminary Operation and Maintenance Manual (POMM 9-1005-294-14) for the “Submachine Gun 5.56mm, CAR-15.” Colt introduces multiple improvements including a smaller telescoping stock/buffer assembly, redesigned round handguards, which were held in place with a wedge-shaped slip ring, and the “noise and flash suppressor.” The suppressor incorporates multiple expansion chambers to slow and cool the propellant gases, thus reducing the muzzle blast from the short barrel. This is particularly important as safety certification was previously withheld due to the high sound levels recorded during testing at Aberdeen Proving Grounds. (However, the same device is later ruled to be a NFA-restricted “silencer” by the BATF.)

The Marine Corps Landing Force Development Center publishes “Marine Corps Position on Small Arms.”

USMC Commandant General Wallace M. Greene reviews results and recommendations of special study group formed to analyze the SAWS study, along with all other references and small arms. General Greene concludes:

  1. 5.56mm rifles and automatic rifles are superior to 7.62mm counterparts in firepower and system weight;
  2. There is no significant difference between the 5.56mm rifles; and
  3. The Stoner 63 MG is not an acceptable substitute for the M60.

General Greene decides that the XM16E1 should be procured for WestPac Marines, and further evaluation is needed for the Stoner 63 concept.

CDC also publishes “Army Small Arms Weapons Systems Study (SAWS) Troop Acceptability Test” and “Threat Considerations for the Small Arms Weapon Systems Study (SAWS).”

The US Army approves shot peening the bolt face and chrome plating the interior of the carrier key.

Edgewood Arsenal publishes “Wound Ballistics of 7.62-mm and 5.56-mm Rifle Bullets at Long Range and Transonic Velocity.”

For a second month, a shortage of M16 and M14 rifles results in the issue of M1 rifles to some units in the US. Combined with September, ~15,000 M1 are issued.

After widespread reports of stoppages and other malfunctions, General Westmoreland requests technical assistance. A team including Colonel Yount’s assistant LTC Herbert P. Underwood, representatives from WECOM, and Colt are sent to Vietnam to investigate. A near total lack of maintenance and cleaning is blamed. Underwood is so appalled that he insists that Colonel Yount come to Vietnam to witness the conditions himself. Yount complies with the request in November. Colt’s Robert Fremont is sent to Rock Island to examine rifles returned from Vietnam. The Technical Assistance Team splits into four units of two men apiece. They visit units and provide maintenance instruction through December. The survey team verifies the existence of a malfunction problem and supports the findings of a preliminary investigation by concluding that the malfunctions are primarily due to inadequate cleaning, improper lubrication, and the continued use of worn parts. The most common faults observed are:

  1. excessive oil on the weapon;
  2. carbon buildup in the chamber, bolt, and bolt carrier group;
  3. overloading of magazines with 21 rounds of ammunition;
  4. oil and grit inside magazines (frequently accompanied by lubricated ammunition); and
  5. failure to replace worn or broken extractors and extractor springs.

Other deficiencies noted frequently are shortages of technical manuals, cleaning equipment, and repair parts, and a general lack of knowledge of the M16 among officers and noncommissioned officers.

Colt initiates work on chrome plated chambers.

Colt reports to the TCC on the issue of reverting to 1-in-14″ twist barrels. Colt indicates that existing rifle barrels already have a 10 percent rejection rate due to tested accuracy, despite meeting physical machining specs. Colt states that a change to the slower rate of twist would require relaxed accuracy standards.

General Johnson reviews the CDC SAWS Study, the Army Staff position, and the FPAO review and evaluation. Johnson decides to draw together the various activities of small arms developments under unified management.

The CDC publishes “Review and Analysis of the Evaluation of Army Combat Operations in Vietnam.” It is a evaluation of the USARV‘s ARCOV findings and recommendations. The CDC concurs with the recommendations that all maneuver battalion riflemen in Vietnam be equipped with the XM16E1, that the XM16E1 replace the M1911A1 (pending the evaluation the CAR-15 submachine gun), and that grenadiers be armed with a dual purpose weapon, specifically the XM16E1/XM148. They note that these recommendations have potential worldwide application. As such, they should not be implemented as such until the SAWS and Infantry Rifle Unit Study 1967-1975 (IRUS-75) projects are completed.

SAPD 253B is amended.

3,033 XM16E1 are shipped to Fort Polk.

Planned deliveries of XM16E1 to allied troops in South Vietnam are suspended. (At one point, there was a suggestion to provide South Vietnam with a military assistance grant of 126,862 XM16E1.)

The US Army initiates work on Delrin charging handle latch to prevent wear to the upper receiver.

The US Army approves a RTA for a dimension change on the charging handle. Colt is awarded $1,500.

DuPont delivers 137,259 pounds of IMR 8208M to the US Army for loading 5.56mm ammunition at government ammunition plants.

Frankford Arsenal finalizes drawings for the XM200 Blank.

With Springfield Armory scheduled for closure in 1968, WECOM realizes that no one will be left to compete with AAI for the SPIW contract. Industry representatives are invited to Fort Benning to witness SPIW testing in hopes of someone picking up the Springfield design. One of the representatives is Colt’s Engineering Project Manager, Robert Roy. Needless to say, Colt is curious to see what is competing against their M16 rifle; they have even gone to the extent of creating a 5.56x45mm fléchette load with a companion smoothbore M16.

Along with the Industry Meeting, the SPIW Executive Committee also convenes. The BRL submits data indicating that the three round burst and full automatic modes of fire of the SPIW are equal in effectiveness. Thus, it is argued that the full automatic mode can be removed from the SPIW to reduce complexity of the trigger mechanism. The OPMR‘s Charles Rhoades lays out the advantages of each mode of fire, but agrees that eliminating the full automatic mode may not reduce the SPIW‘s effectiveness. COL Yount asks the BRL to design and conduct a test which would compare the relative hit capability of the controlled-burst versus full automatic modes of fire. Later in the month, a subcommittee consisting of representatives from the USAIB, TECOM, Frankford Arsenal, CDCIA, and BRL meet to discuss the BRL‘s proposed test plan.

The USMC asks Cadillac Gage to upgrade 286 of their early Stoner 63 to the 63A standard.

FN builds its third CAL prototype.

Colt’s Karl Lewis and Robert Roy receive US Patent #3,279,114 titled “Grenade Launcher.”

General Johnson announces his recommendations from the SAWS study in the memo CSM 66-485 “Army Small Arms Weapon System“:

  • The XM16E1 rifle will be adopted as the standard Army rifle and will be reclassified as “Standard A”. The M14 and M14A1 rifles will remain “Standard A” initially. The Authorized Acquisition Objective (AAO) for rifles and automatic rifles will be computed on the XM16E1, rather than on the M14 and M14A1.
  • Pending the completion of…field experimentation…the XM148 grenade launcher will be issued as the companion grenade launcher for units armed with the XM16E1 rifle. Concurrently, action will be taken to improve the design of the XM148.
  • The Colt carbine/submachine gun will be adopted in lieu of the XM16E1 rifle in those cases where use of the XM16E1 rifle is impractical as the individual weapon.
  • A companion automatic rifle will not be adopted.
  • The M60 machine gun will be retained until an improved machine gun is developed and adopted. Evaluation of the 5.56mm machine gun will continue.
  • The development cycle of the SPIW will be reoriented to the status of exploratory development and become a part of a broadened small arms research and development program for the future.
  • The overall procurement objective is a single-family (rather than a multi-family) small arms weapon inventory based on the Colt 5.56mm individual weapons and, for the present, the M60 machinegun; and the first objective will be to eliminate at an early date the caliber .30 family of infantry weapons.
  • Product improvement…will be incorporated in the new production of XM16E1 rifles and 5.56mm ammunition.
  • The 7.62mm duplex ammunition will not be produced for other than development purposes at this time.

COL Yount and LTC Underwood visit II Field Force HQ, the commanders of the 25th Infantry Division and 1st Aviation Brigade, 1st Cavalry Division, 1st Infantry Division, and LTG Walt, Commanding General III MAF. Yount starts investigation into the rifle’s finish and chrome plating of chambers. In addition, he emphasizes advance shipments of repair parts and cleaning materials.

The decision is made to issue the M16 to division base units of the 9th Infantry Division.

25 XM16E1 are issued to each USMC infantry battalion for training in Vietnam.

Colt delivers its first shipment of 1,190 Commandos to the military. These are quickly routed to South Vietnam.

The US State Department’s Office of Munitions Control approves the export sale of 18,000 AR-15 and 2,300 AR-15 HBAR M1 by Cooper-Macdonald to the Republic of Singapore. Only 513 are shipped before Colt severs their relationship with Cooper-Macdonald. Colt then reapplies for a license to export the original amount of rifles to Singapore.

DuPont delivers 182,746 pounds of IMR 8208M to the US Army for loading 5.56mm ammunition at government ammunition plants.

The military specification for the XM200 Blank, MIL-C-60616, is released.

Ten round stripper clips enter production.

COL Yount is ordered to supervise development and procurement of scopes and mounts for WECOM.

General Electric’s Chemical Materials Department proposes a disposable polymer-bodied magazine for the M16.

With the assistance of the USAIB, the BRL conducts SPIW mode of fire testing at Fort Benning.

The USAIB recommends to General Johnson that the SPIW program be cut back, with greater responsibility given to AAI to develop a working model.

COL Yount terminates the current testing of the SPIW at Aberdeen and Fort Benning. Yount directs the submission of a final report to cover all subtests either partially or fully completed.

The USAIB publishes “Engineer Design Test for Special Purpose Individual Weapon (SPIW).”

Frankford Arsenal files the report “SPIW Ammunition Cost Estimate Study.” The report claims that fléchette cartridges could be produced economically given enough study and effort.

In an internal memo at Colt, Robert Roy reports that there is no reason to save the Springfield SPIW, as the program is unlikely to be debugged anytime soon. Moreover, such efforts would only serve take attention away from Colt’s own M16.

Testing of the XM177-series flash/blast suppressor begins with an objective of reducing flash signature.

Colt reaches the production capacity of 25,000 rifles per month.

The JCS reallocates the distribution of the XM16E1 rifle for the period November 1966 through June 1967. At the same time, provision is made for the delivery of 4,000 XM16E1 to Thailand in increments of 1,000 beginning with March 1967 production.

AMC General Counsel Barnes meets with Colt’s Benke, Gubbins, Ford, and Hall over production rights and the TDP. The Army claims a future requirement of one million rifles over the next four years. A second source of production is required, but it would be agreeable to the facility being owned by Colt. The Army foresees production at the second manufacturing facility representing ~10,000 rifles per month. The Government would be willing to fund this facility with $3-5 million plus tooling. Benke responds that it would not be worth Colt’s effort to start a second facility for production less than 12,500 rifles per month. Moreover, Benke insists on staying with his earlier proposed $9 million license fee, but announces that Colt is willing to invest the entire amount into the second facility in exchange for maintaining proprietary rights to the M16. Colt also desires to exclude rights for second sourcing magazines and parts that are already produced in house at Colt. Barnes counters that production of 12,500 rifles per month at a second facility would result in excess capacity. Barnes then threatens to contact the president of Colt’s parent company Colt Industries, George A. Strichman, to get their best offer. During the meetings, it becomes apparent that Colt’s representatives have access to the Army’s estimates for future requirements and to the Army’s plans for expansion of the production base. When this fact is brought to the attention of Army Chief of Staff General Johnson, he directs DCSLOG LTG Lincoln to prepare a memorandum establishing AMC General Counsel Barnes and COL Yount as the single points of contact with Colt until negotiations are completed. Barnes later writes a memorandum for record titled “Negotiations with Colt’s re. Rights to M16 and XM16E1 Rifle.”

The next day, Colt’s Benke and Gubbins call Barnes requesting clarifications. Barnes states that the first 150,000 rifles of any competitive solicitation will be reserved for Colt, and the next 100,000 will be awarded to the second source contractor. However, a third source will be considered if more than 250,000 rifles are required. The Government will require the right to manufacture and procure parts from other countries; however, production of whole rifles will remain in the US. In addition, any agreement will require a substantial reduction in the proposed $1.8 million fee to reproduce the TDP. Moreover, royalties could be no higher than 0.5 percent over those owed Fairchild and Cooper-Macdonald.

The Technical Assistance Team submit their findings to General Besson. They again point out the lack of maintenance, the shortage of cleaning equipment and spare parts, and the general lack of knowledge and training by officers and NCO regarding the proper care of the rifles. As a result of the technical team’s visit to Vietnam, the following action is taken:

  1. Instruction material on the care and cleaning of the M16 is published and distributed at company or rifleman level;
  2. Emphasis is placed on the need for adequate command supervision of maintenance programs;
  3. New troops are required to receive a minimum of two hours M16 maintenance training during their first week in Vietnam; and
  4. Immediate USARV inspection and repair of all Ml6s on hand by divisional direct support maintenance teams and elements of the 1st Logistics Command is directed.

The USARV distributes a preventive maintenance pamphlet for the XM16E1.

Colt conducts in-house testing of chrome plated chambers.

Colt begins equipping new production rifles with Sturtevant’s improved buffer. The first 8,000 to 10,000 rifles produced during the month have the older buffer. Retrofit of older rifles with the new buffer will not be complete for nearly a year.

Frankford and Rock Island Arsenals report that they cannot find a cause of the reported “blow-ups.” Only cartridges loaded with inappropriate powders (handgun or shotgun-type) caused the same level of damage during testing.

Secretary of the Army Resor sends a memorandum to McNamara outlining General Johnson’s recommended objectives for the rifle program:

  1. Rifle procurement should be limited to the XM16E1 for the near future;
  2. Steps should be made to replace the remaining M1 rifles and M1918 BAR in Army inventory with XM16E1 as soon as possible;
  3. Long term planning should concentrate on replacing the M14 with XM16E1;
  4. A second XM16E1 manufacturer should be provided for in the FY 1968 budget; and
  5. Small arms research and development should be accelerated to bring about further major improvements.

The memorandum further states that the XM16E1 is generally superior for Army use, the SPIW program is unlikely to delivery a satisfactory weapon in the near term, and some minor changes are justified in the M16 and its ammunition. This would include a change of propellant and the barrel’s rate of twist.

The DOD Program Budget Decision approves the Army’s request for FY 1968 procurement of 175,000 XM16E1 rifles, but limits the funding to $31.2 million. The Army had requested $35.7 million, which included $9 million for acquiring patent rights and $0.8 million for the TDP. The Army appeals the DOD‘s decision, but is denied.

The US Army awards a $6,908,750 contract modification to Colt for 10,000 XM16E1 and 65,000 M16. Another contract modifications is awarded for 27,531 rifles.

1,127 XM16E1 are shipped to Fort Polk.

The US State Department’s Office of Munitions Control approves the export sale of 45 AR-15 to West Germany.

McNamara directs that the issue of XM16E1 to ARVN and ROK forces be deferred, and that the allocations previously planned for these forces be redirected to US units.

D&PS publishes “Engineer Design Test of Modified Flash Suppressor for 5.56mm, CAR-15 Submachine Gun.”

TECOM sends the message “PI Test of XM177E2, Submachine Gun.”

DuPont delivers 187,847 pounds of IMR 8208M to the US Army for loading 5.56mm ammunition at government ammunition plants.

COL Yount receives a directive from General Besson to “come to grips at an early date with the 3,250 f.p.s. velocity requirement.”

WECOM appoints Christo W. Kantany as the new QAR assigned to Colt. At the time of his assignment, Kantany is notified by DCASD-Hartford supervisory personnel that the company has a good quality control program and no serious problems were anticipated with Colt in the manufacture and quality control of the M16A1 rifle.

Frankford Arsenal issues the report “A Summary of Mathematical Methods in Hit and Incapacitation Probability Analysis of Small Arms Weapons Systems.”

The US Army approves a RTA for a dimension change of the disconnector. Colt is awarded $242.60.

Colt’s Foster Sturtevant receives US Patent #3,292,492 titled “Trigger Mechanism,” the four-position selector switch.

General Electric’s Robert E. Chiabrandy files three patent applications related to the design of a lightweight Minigun-style weapon suitable for small caliber cartridges like the 5.56x45mm.

The first XM148 grenade launchers arrive in Vietnam.

Gene Stoner receives US Patent #3,293,986 titled “Magazine for Belted Ammunition.”

(Next: 5.56mm 1967)

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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