The 5.56 X 45mm “Timeline” – 1975

A Chronology of Development by Daniel E. Watters



The US Army Small Arms Program (ARSAP) is renamed the Small Caliber Systems Program.

A second phase of the FABRL experiments plays with adding “fumer” or “base bleed” technology to reduce the drag even further. Base drag of the “Von Korman” projectile is calculated as 63 percent of the total drag. Base bleed technology is estimated to give a reduction of 75 percent of base drag, and thus cut overall drag by half.

Thiokol Corporation publishes the report “Prevention of 5.56mm Aluminum Cartridge Case Burnthrough.”

The US provides a military assistance grant of 7,819 M16A1 to South Vietnam.

The US provides a military assistance grant of 2,101 M16A1 to Cambodia.

The US provides 1,148 M16A1 and 66 M203 to Indonesia as part of a military assistance package.

The US provides 14,546 M16A1 to Thailand as part of a military assistance package. Prior to this 61,084 M16A1 had been provided though military assistance packages. A separate FMS is made of 2,822 M16A1.

The US makes a FMS of 18,000 M16A1 to Jordan.

The Philippine government receives 35 M16A1 through FMS and 22,991 more through the MAP.

CDEC publishes “Army Small Arms Requirements Study II – ASARS II: Experiment FC008A, Final Report.”

After eight years of testing, Frankford Arsenal has evaluated sixty different sight systems from which five main concepts emerged. Two of these are considered significant improvements. The two concepts are early versions of iron night sights using “promethium” and non-magnifying “reflex sights.” The reflex sight is considered superior. The leading model at this point is the Reflex Collimator Sight (RCS) designed jointly by Frankford’s Fire Control Laboratory and AAI. The preferred reticule consists of three small yellow wedges configured in an inverted ‘Y’.

The US Army’s 12th Special Forces Group evaluates the US Navy’s Mk 2 Mod 0 Blast Suppressor.

Frankford Arsenal publishes the report “Caseless ammunition technology (5.56MM & 7.62MM).”

Hughes delivers a prototype of its Advanced Light Machine Gun (ALMG) with 2,000 rounds of 5.56x30mm “chiclet” ammunition. L. James Sullivan is responsible for the ALMG‘s design, based upon Morris Goldin’s “lockless” principle. The 5.56mm cartridge uses a 68-grain projectile launched at ~3,000 fps.

HK introduces the compact HK 53.

SIG introduces the SG543 carbine.

Dr. Louis Palmisano begins to trounce the competition and smash records at high-profile Benchrest matches while using rifles chambered for his new .22 PPC and 6mm PPC cartridges.

The British initiate Phase I of the IW/LSW‘s initial development stage. The goals are to improve the 4.85mm cartridge, the IW, the LSW, and the SUSAT. New prototype models of the latter three are developed for further testing. The 3 round burst mechanism is deleted from the new IW and LSW prototypes, the magazine release is moved from the right side of the receiver to the left side, a lever switch replaces the push-through selector button, and a tungsten inertia pellet is placed within the bolt carrier. At least one IW is configured for left-hand use, and one LSW prototype is produced with a quick-change barrel.

The Argentine Army General Staff’s Operations Division publishes the basic requirements for an assault rifle.

Chile purchases ~500 HK 33. (One source claims delivery of 4,000 rifles.)

The Royal Thai Armory begins production of the HK 33.

Frankford Arsenal publishes “On the Accuracy of Flechettes by Dynamic Wind Tunnel Tests, by Theory and Analysis, and by Actual Firings.”

ARMCOM publishes the report “System Assessment for the 5.56mm Rifle M16A1.”

Rodman Laboratory publishes “Life Cycle Time and Cost Estimates for Squad Automatic Weapon System Candidates.”

Frankford Arsenal publishes the report “Prevention of 5.56mm Aluminum Cartridge Case Burn-Through.” This report documents recent developments in cartridge case coatings designed to prevent the occurrence of burn-through in 5.56mm aluminum cartridge cases. The research work performed determined the effectiveness and general feasibility of five materials: red grip core paste, polyimide varnish (DuPont), NASA’s 45B3 intumescent coating, polysulfide sheeting, and RTV-734 (Dow Corning) used in combination with other materials. As a result of test firings conducted using the aforementioned materials, two formulations, the NASA intumescent coating and the polysulfide sheeting, internally applied, emerged as the most successful candidates. In light of the general efficiency demonstrated by these materials, it is concluded that an internally applied case coating materiel could prove to be most effective in the prevention of burn-through 5.56mm aluminum cartridge cases.

Thiokol Corporation publishes the report “Development of a Flexible Internal Element (FIE) for Aluminum Cased Ammunition.” The primary purpose of this study was to develop an FIE composition that could be preformed and perform at least equally to a liquid FIE. (The latter had already been tested successfully by Frankford Arsenal.) A preformed FIE and an experimental fabrication process had to be established prior to manufacturing a quantity of 6mm aluminum cases for the SAW program. For convenience, 5.56mm cases were used before 6mm cases were available. A series of FIE sealing cups were fabricated from several polysulfide formulations and test fired. Of the formulations tested, three types, identified as P10, P18, and P28, were effective in preventing erosion and flash, otherwise known as burn-through, in aluminum cased ammunition.

Aberdeen publishes the report “Product Improvement Test of CMR-170 Propellant for Cartridge, 5.56-MM, Ball M193.” (CMR is short for Canadian Military Rifle.)

The AMC publishes “Analysis of Dispersion Measurements for the M16A1 Rifle with Chrome Plated Bore.” This report is a result of the higher than expected wear out rate of barrels used on the M16A1 rifle during its use in Vietnam. The wear out rate was due to the normal mechanical erosion plus the corrosive effect of the Vietnam environment. To correct this problem, it was decided to chrome plate the bore of all replacement barrels. The sample barrels selected from three manufacturers were fired until they were worn out with accuracy checks taken after each thousand rounds fired. The average value of the extreme spread measure of dispersion was used to establish acceptance and rejection criteria for new barrels and to establish the amount corresponding to a worn out barrel.

Andrew J. Grandy receives US Patent #3,861,308 titled “Ammunition and Weapon Systems.”

Aberdeen’s HEL publishes “Observation Test of External Tracer Ammunition.” As a preliminary study of the utility of one concept of “external tracer”, five types of chemically coated ball ammunition (which when fired, left visible vapor trails to mark projectile trajectory) were compared with 7.62mm M62 tracer, 5.56mm M196 tracer and 7.62mm ball ammunition on two measures of observation. Twenty infantrymen reported after each of 80 single rounds whether tracer was detected and which of three targets 400 meters downrange was engaged. Standard tracers (M62 and M196) were associated with substantially more accuracy in ammunition target identification than external tracers. Only when observers in daylight were located directly behind the weapon firing were they able to detect external tracer with an accuracy approaching that of standard tracer.

Aberdeen releases the report “Comparison Test of Rifle, 5.56-MM, M16A1 with M203, 40-MM Grenade Launcher.”

The US Army Arctic Test Center ends testing of an improved M203 design. A total of 1000 rounds of 40mm M433 HEDP ammunition was fired from each of five improved M203 launchers. Cold weather performance characteristics of the 40mm M433 HEDP ammunition were recorded and reported for information only.

The AMC publishes “Correlation of Breech Erosion Gage to Accuracy for M16A1 Rifle with Chrome Plated Barrel Bores.” The research was designed to answer the following questions: 1) Do calibrated gauge rods act as good predictors of accuracy extreme spread, and 2) What gauge rod diameter gives the best performance? Data was obtained from M16A1 rifles fired at different rates for the life of the rifles. For each rifle, extreme spread was recorded along with the corresponding gauge reading at periodic intervals. The data was then analyzed to determine a relationship between the extreme spread dimension and the gauge reading. The report concludes that gauge rod readings are not an accurate predictor for extreme spread. However, the 0.2206 inch gauge rod gave the best prediction of performance.

Rodman Laboratory releases the report “M16A1 Thermal Barrel Firing Test.”

Frankford Arsenal publishes the report “The Design, Manufacture, and Ballistic Assessment of Special 5.56mm Bullets.”

HK‘s Günter Kästner, Dieter Ketterer, Tilo Möller, and Ernst Wössner file an US patent application for the design of the G11.

Andrew J. Grandy receives US Patent #3,872,615 titled “Ammunition and Weapon Systems.”

The Republic of South Vietnam collapses. Over 946,000 M16-type rifles are lost. Many find their way into the hands of various Communist insurgent groups during the late 1970s and ’80s.

On behalf of the US Army, Leonard R. Ambrosini and Charles N. Bernstein receive US Patent #3,875,864 titled “External Tracer Projectile.”

Frankford Arsenal publishes the report “Coefficient of Friction of Brass or Gilding Metal on Nylon.” It was found that the high frictional forces believed required for successful firing of gilding metal jacketed .17 caliber bullets and glass-filled nylon sabots could be attained by surface modifications.

The US Army Arctic Test Center publishes “Check Test of Launcher, Grenade, 40mm, M203, under Arctic Winter Conditions.” The report concludes that the previously reported problems had been corrected and that the improved M203 launcher can be operated successfully in the arctic winter environment. It is recommended that the improved M203 launcher be considered acceptable for use in the Arctic.

Abe Flatau receives US Patent #3,877,383 titled “Munition.”

The Singaporean Ministry of Defense notifies the US Embassy that the Thai Army Chief of Staff General Kriangsak has requested immediate delivery of 50,000 M16S rifles.

Aberdeen’s HEL publishes “An Exploration of the Contribution of Strike Feedback to Combat Effectiveness with Ball and Tracer Ammunition.” A field test was conducted in which 22 machinegunners each engaged double E-type silhouette targets at ranges from 350 to 650 meters with the M60 and Stoner 63 machineguns during daylight with ball ammunition and the 4:1 ball:tracer mix in a test of the hypothesis that targets would be hit faster and with fewer rounds if located on strike feedback-enhancing terrain. Intervening factors precluded a clear answer to the question, but suggested that it might be of less importance than other factors. Data are analyzed for the performance measures percent targets hit, number of bursts per engagement, and score.

Frankford Arsenal publishes “The Effect of Statistical Velocity Variation on the Gaussian Bivariate Probability of Hit for Small Caliber Systems.” The statistical variations in both the average velocity and the linear standard deviation of velocity, due to the location of propellant airspace, are investigated by trajectory conversions to errors on a vertical target and by calculations of rectangular hit probabilities with the Gaussian bivariate distribution. The two cartridges examined are the 7.62mm, Ball, M80 and the 5.56mm, Ball, M193. Sources of errors and their magnitudes are discussed. Two diverse levels of aiming error are assumed, corresponding to present requirements for the Future Rifle System. The range-dependent errors due to velocity variations are treated as perturbations of the ballistic error. The nose-tap (NT) procedure of chambering cartridges is compared to the standard base-tap (BT) procedure. The changes in hit probability due to the statistical velocity variations corresponding to the BT and NT air space positions are shown to be insignificant for these two standard cartridges.

The BRL publishes “Lethality Estimates for Various Squad Automatic Weapon (SAW) Contenders.”

Frankford Arsenal publishes “Ammunition Weapon Interface of the 6 mm Dual Piston Squad Automatic Weapon (SAW).”

The French Defence Ministry resumes development of the FAMAS.

Paul Tellie files an US patent application for the FAMAS’ twin ejection ports and its cheekpiece/port cover.

Paul Tellie also receives US Patent #3,882,625 titled “Breech Mechanism for Guns.”

Remington releases the report “Advanced Development, XM742 Soft RAG Projectile.” Their development work has been performed on contract to Edgewood Arsenal.

Personal Defense Weapon (PDW) System Ammunition Summary Report” is published.

Singapore pays Colt $638,170 in back royalties for the M16S.

The Thai requirement for Singaporean M16S has increased to 60,000 with immediate delivery required of 30,000 rifles. In negotiations between the Singaporean Ministry of Defense’s Director of Military Industries, Mr. Ong Kah Kok and Colt’s President David C. Eaton and Vice President Fiddler, Colt indicates that they would like make a direct sale to Thailand. Mr. Ong warns that any attempt by Colt to take the Thai contract would result in an anti-Colt campaign in Southeast Asia. Ultimately, both parties compromise on providing the Thai 30,000 rifles apiece.

Rodman Laboratory publishes “Projectile Engraving Mutations and Their Relationships to Accuracy of the M16A1 Rifle.” A two-phase test program was conducted in order to evaluate the hypothesis that changes in the accuracy of a rifle are reflected in changes of the engraving patterns found on projectiles fired from that rifle. Three mutations of projectile engraving characteristics were isolated. These mutations were: 1) widening of the grooves engraved in the projectiles; 2) increasing variation in the lengths of the grooves on a bullet; 3) the appearance of surface mutilation on the bullet jackets. Each of the mutations demonstrated some correlation with accuracy. The widening of the grooves correlated best with accuracy, exhibiting correlation coefficient above 0.7 over a wide range of firing rates, ammunition types, and barrel manufacturing processes.

Gulf + Western’s Advanced Development & Engineering Center publishes the report “Final Report on Feasibility Study of 5.56MM Plastic Body/Metal Insert Cartridge Case.”

Andrew J. Grandy receives US Patent #3,890,730, US Patent #3,890,732, US Patent #3,890,878, and US Patent #3,890,880, all titled “Ammunition and Weapon Systems.”

Aberdeen’s BRL publishes the report “The Influence of Muzzle Gasdynamics upon the Trajectory of Fin-Stabilized Projectiles.”

Mid 1975:
The South Korean M16 plant has completed ~150,000 rifles. Due to inflation, the production program now requires an extra $10 million in funding over and above the original budget of $42 million. Korea desires to speed up production for completion by September 1977 versus April 1979.

The Infantry Board concludes a six-month trial of twenty-five Frankford/AAI RCS with 28 rifles, using 66,230 rounds of ammunition. Nothing more comes of the project.

The US Army awards $35,000 to Colt as part of the 1967 Licensing Agreement.

WAC recruits begin a forty hour defensive weapons training course, including the M16A1 rifle. Firing of the weapons is now mandatory.

Rodman Laboratory releases the report “External Barrel Temperature of the M16A1 Rifle.” The work is part of a Product Improvement Program to improve the M16A1 barrel’s accuracy life. One of the goals is to reduce bore temperatures by optimizing the heat transfer characteristics of the barrel’s exterior profile. The report establishes a base line from which this work can proceed.

Morris Goldin receives US Patent #3,892,181 titled “Flat telescoped cartridge casing.”

The US Army awards a $17,000 contract modification to Colt related to the M16. The Army also deallocates $22,000 related to the 1967 Licensing Agreement.

Secretary of Defense Schlesinger requests and receives confirmation from the US Defense Attaché Office – Singapore that a Thai Navy vessel had left Singapore with a cargo of M16S. The US had not approved the deal nor had it received assurance from Thailand that the rifles will not be resold. The Singaporean government claims that they went forward with the transaction due to extreme political pressure from the Thai government. They claim that the rifles will be returned to Singapore if the US does not approve the sale.

The US Army awards a $57,000 contract modification to Adventure Line Mfg. Co. Inc.

Abe Flatau, Donald N. Olson, and Miles C. Miller receive US Patent #3,898,932 titled “Non-Hazardous Ring Airfoil Projectile for Delivery of Non-Lethal Material.”

MAS completes the A5 prototype of the FAMAS.

The US Army awards $1,576,000 and $1,214,000, and deallocates $664,000 from Colt in contract modifications related to the M16. The Army also awards $26,000 to Colt as part of the 1967 Licensing Agreement.

On behalf of the US Army, Curtis D. Johnson, Lonnie D. Antwiler, Larry C. McFarland, Arthur R. Meyer, Fred J. Skahill, Doyle L. White, Keith L. Witwer, and Richard L. Wulff file a patent application for the design of the XM235.

On behalf of the US Army, Hugh D. MacDonald, Jr. and Peter Tietz file a patent application for the “fumer” projectile design.

The military specification for M197 High Pressure Test, MIL-C-46936B, is amended.

The State Department notifies the US Embassy in Malaysia that it is willing to approve a request for various military equipment, including 101,800 M16 and 30 million rounds of 5.56mm ammunition. Congressional approval will be sought for FMS guaranteed loans through FY 1979.

Rodman Laboratory releases the report “Study of Man-Weapon Reaction Forces Applicable to the Fabrication of a Standard Rifle Firing Fixture.” A study was conducted of the man-weapon interaction force relationship to define the parameters to be incorporated in the design of a universal small arms test fixture, which simulates man as a flexible mount. The mathematical simulation was supported by an extensive test firing program, involving shooters of various sizes firing the M16 rifle, and the M79 and M203 grenade launchers. In these tests, the shoulder reaction force and the dynamical motions of the man-weapon system were recorded.

Andrew J. Grandy receives US Patent #3,913,445 and US Patent #3,913,446, each titled “Ammunition and Weapon Systems.”

NATO‘s AC/225 Panel III, Subpanel 4 issues “Operational Requirement for Individual Weapon.”

Secretary of Defense Schlesinger approves an amendment to the South Korean M16 MOU, increasing the FMS credits by $10 million and authorizing accelerated rifle production.

Paul Tellie receives US Patent #3,916,530 titled “Sighting Means for Firearms.”

The US Army announces their plans to establish an Armament Development Center and an Armament Logistics Command.

The US Army awards a $2,170,000 contract modification to Colt related to the M16.

Rodman Laboratory publishes “Calibration of Breech Erosion Gage for 5.56mm Chrome-Plated Bores.” A firing test was conducted to provide a database for the optimization of the design of a breech erosion gauge for 5.56mm chrome plated rifle barrels. Nine separate gauge diameters, 27 barrels, three rates of fire, two types of ammunition, and three barrel manufacturers were represented in the test to give the broadest possible database. Analysis of the firing test led to the determination that the optimum gauge diameter range is from 0.2210 – 0.2218 inch, and that barrels should be rejected when gauges within this diametrical range penetrate more than 2.62 inches beyond the rear of the locking lugs on the barrel.

Rock Island Arsenal publishes the report “Cold Rotary Forging of Small Caliber Gun Barrels.” The objective of this program was to provide an improved method of manufacturing military gun barrels ranging in bore size from .17 to .50 caliber. (This includes barrels for the M16.) During this project, suitable equipment was purchased from GFM Machines in Austria, and a pilot line for cold rotary forging of barrels was established. Excellent bore qualities, reproducibility, reduced process time and reduced tooling costs were demonstrated. By rifling, chambering, and simultaneous exterior contouring, many conventional machining operations were eliminated with a gain in production rate. The cold rotary forging of gun barrels has been implemented as a production process for the Rock Island Arsenal.

Aberdeen’s HEL publishes the report “Human Factors Evaluation of A Rifle-Launched Rocket Projectile.” An experimental investigation was made of the aiming and cant errors associated with the firing of a rocket round from the muzzle of a rifle. The unusual features of the system were an appreciable weight at the muzzle (5-7 lbs) and an appreciably delay (.3 second) between ignition and launch. If ignition is accomplished by firing a ball round from the rifle, launch errors of 4-7 mils may be expected. If the ignition is recoilless, errors of 2 mils may be expected. Cant errors of about 1.40 deg appear typical.

(Next: 5.56mm 1976)

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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