Historical Document · 1992
The US Army's summary report of the Advanced Combat Rifle programme (Picatinny Arsenal, February 1992; DTIC AD-B162 942), with the contractor synopsis in Appendix B. The Hyper-Burst Mechanisms dive's main source for the H&K G11 and the other ACR entries in the US test; the Daisy dive cites it on caseless ammunition.
. '' L@ .A D-B 162 942 I\1\\\11\Ill1\ \ IIIIII t\111 IIIII Ill\\Ill A~-E402 286 Technical Report ~RCCD- TR-92001 ADVANCED COMBAT RIFLE (.AGIIJ PROGRAM VOLUME I, AC'R ~AOG· AAM SUMMARY OTIC S . D ELECTE D l I AP~ 0 3 199~ Vernon E. Shisler Stephen M. Mango February 1992 U.S. ARMY ARMAMENT RESeARCH, DEV.ELOPMENif AND ENGINEERING CENTER Close Combat Armaments Center Picatinl'ily Arsel'ilal, New Jersey US ARMY ARMAMENT MUNITIONS & CHIEMICAL COMMAND ARMAM[NTlii5E CENTER ~· Distribution~ U.S. Government agencies only; test and evaluation and ~roprietary information; February 1992: Ottler requests for this doGUment must be referred to ARDEC, ATTN: SMOAR-IMI-1, Picatinny Arsenal, NJ Q7806-!iO:,: OC;:_ ):--~~~-=----~~--~ DIGITIZED FOR YOUR REVIEW AT WWVI.SMALLARMSOFTHEWORLD.COM I ·~.' I REPORT DOCUMENTATlON PAGE Form Approwd OMS No. 0704-0188 Public reporting burden for this collection of information is estimated to av8fage 1 hour per response, including the lime for reviewing instructions. searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestlons for reducing this burden, to Washington Headquarters Services, Directorate for Information Operation and reports, 1215 Jefferson Davis Highway. Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwortt Reduction Project (07040188), Washington, DC 20503. 1. AGENCY USE ONLY (Leaw blank) 3. REPORT TYPE AND DATES COVERED , 2. REPORT DATE February 1992 FinaV1982 to 1991 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS ADVANCED COMBAT RIFLE (ACR) PROGRAM, VOLUME I, ACR PROGRAM SUMMARY TAC DAAA21-90-D-0005 Delivery Order 0007 . 6. AUTHOR(S) Vernon E. Shisler Stephen M. Mango 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESSES(S) 8. PERFORMING ORGANIZATION REPORTNU~R ' ARDEC,CCAC Joint Service Small Arms Program (JSSAP) Office (SMCAR-CCJ) Picatinny Arsenal, NJ 07806-5000 9.SPONSORINGIMONITORING AGENCY NAME(S) AND ADDRESS(S) Tei:hnical Report ARCCD-TR-92001 10. SPONSORING/MONITORING AGENCY REPORT NUMBER ARDEQ,IMD STINFO Br (SMCAR-IMI-I) Picatinny Arsenal, NJ 07806-5000 •' I 11 . SUPPLEMENTARY NOTES The ACR final report was prepared in a multivolume format to permit separation of major subject areas. The ACR Program Summary (Volume I) is the primary volume. Volumes II through VII contain detailed infonnation on specific areas within the overall ACR program. 12a DISTRIBUTION/AVAILABIUTY STATEMENT 12b. DISTRIBUTION CODE ~U.S. Distribution Government agencies only; test and evaluation; proprietary information; February 1992. Other requests for this document must be referred to ARDEC, ATTN: SMCAR-1~1 -1 , Picatinny Arsenal, NJ 07806-5000 13. ABSTRACT (Maximum 200 words) The Advanced Combat Rifle (ACR) program was a technology base program that investigated ct~rrent rifle technologies to inCfease combat effectiveness owr the current M16A2 rille system. Four cifferent and unique ACR cancidate systems successfully demonstrated various rifle technologies inclucing caseless and plastic cased ammunition, small caliber flechell8 projectiles, high cyclic rate gun mechanisms, and optic sights. The ACR program has significantly advanced the state-of-the-art in rifle technology and will fonn the basis of any future individual weapon requirements. This report documents the entire ACR program from the initial caseless contracts through the completion of the field experiment in 1990. The report documents the programmatic aspects and decisions made during the program and concentrates on the technology investigation efforts. It cisct~sses the planning efforts related to the field experiment and presents general results of the experiment as they relate to the overall program. The details of the field experiment and analysis of the results are documented in separate reports published by the appropriate government organizations. 15. NUMBEROFPAGES 14. SUBJECT TERMS Combat rifles Small caliber Salvo Caseless 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION Of REPORT Of 'THIS PAGE UNCLASSIFIED NSN 7540-01 280-5500 UNCLASSIFIED 16. PRICE CODE 19. SECURITY CLASSIFICATIQfl 20. UMITATION OF ABSTRACT Of ABSTRACT UNCLASSIFIED SAR Standard Form 298 (Rev. 2~9) Prescribed by ANSI Std. Z39-18 298-102 ".. 95 INTENTIONALLY LEFT BLANK ,. f:/ VOLUME I PROGRAM SUMMARY 1i~.S. Distribution Government agencies only; test and evaluation and proprietary information ; February 1992. Other requests for this document must be raftered to ARDEC; ATIN: SMCAR-IMI-1, Picatinny Arsenal, NJ 07806-5000. ., :-: • .... -;o~•4••• w .-> INTENTIONALLY LEFT BLANK .. .... , ..... ~ -.- •.._ , ..., GUIDE TO ACR FINAL REPORT ACR Final Report . ·: BUCK.NER'R~GE INSTRU.~E.tlfATiON:SY_ST.~J!j,. ~p~~T:OJ~~~,~,P.~.l\$;:· ,. ·.· .. ···':.X, :~: .. . ,::.•.;. :·'·::· ACR:U.S.E-~MANUALS': . dPe:iilit~WMi~~~~t~;~b~,·.· -~= • TESTeo·WEA"PON QESIGNS' .H~ttR~Q.~:et~AtfflANQie~o:ou_cJa!t!;rv SUMMA R_'(1,&:.0:EVE~9P,Metm . . ~~s:raRi ..· ·:··::x<'·'· .,,..,,.,. :. . . . . . ··•. ·..::···. :=·..... =.:~:. . . . . . .. :; ... '" .. -~~ :.:~.:-: ' Ji. .il:.~~~x ··:<::: .:: :· •,·.;. ·:: :·:::.. ~;._;_-; ; : •••;•. ~ .;·.;·::;:~~~::?:· ·: : .· PROGJ{AP~tM~_Aq~~-g~?b"®U.M~·~s· PROGR~M" MANAGE"'I;r_q. o6cUMEN'rAtiQRF6~:'A.¢!f~· ' -~· .. .. P.ROG~~M = CQ.t;ff.a.~:r;g_~l:f!-~,~~!! ~.~~J$h . :····: . .. ....•.. ;·: · ". ACKNOWLEDGMENTS ) The Joint Service Small Arms Program (JSSAP) office wishes to acknowledge the outstanding technical support provided by ARDEC's in-house personnel throughout the entire Advanced Combat Rifle (ACR) program. In particular, the ACR office wishes to thank Mr. Robert Pizzola for acting as the ACR Contracting Officer Technical Representative (COTR), Mr. Dennis Conway for ammunition design and flechette development, Mr. Phillip Baker for weapon design and development, Mr. Bruce Brodman for caseless ammunition development, Mr. Edward Rempfer for ammunition producibility, and Mr. John Edwards for optic sight and test range (Buckner, Range) development. The JSSAP office would also like to acknowledge the outstanding support of Mr. James Torre of the Human Engineering Laboratory (HEL) at Aberdeen Proving Grounds, Maryland, and Mr. Eugene Heiss and Ms. Donna Querido of the U.S. Army Material Systems Analysis Activity (AMSAA) also located at APG. . " TABLE OF CONTENTS 1.0 2.0 3.0 4.0 5.0 ·) 6. 0 7.0 lntroduction ..................................... .... ............................................................................................1 1.1 Description of Systems ............ ......................... ............... .................................................... 1 1.2 Program Goals and Objectives ... .... .... .... .... .... .. .... .. ........... .... .... ............... ...... .... .... .............. 2 Backgrou nd ................................. :..... .. .... .... .... .............. ............. .. .. .... ..................... .... ~ ... ...............3 2.1 History ...................... ..... ............................................. :.......................................................4 2.2 OGA Support .............. ...... .... .... ................................... .... ...................................... .............5 Weapon Summaries ...................... .... ....................................... ................................. ..... .... .. .......... :9 3. 1 General ......................... ........ ........... .................. ............. ................................. .. .... .. .... .......9 3.2 AAI .. ......... .............. ............. .... .... .... .... ........... ................ .... ....................... .. .......... .... ....... 10 3.3 Colt .... .... ....................... .... .... .... .... .... ........ .......... .... .... ...... .... ........................... .............. .. .11 3.4 , Heckler and Koch (H&K) ................................... ...... ............................................... ............. 12 3.5 Steyr ............................................. : .................................................... :..... ......................... 14 Engineering Tests ..................... ........................................... .......................................................17 4.1 Backgrou nd ......................................................................................................................17 4.2 Safety and Engineering Tests - CSTA ........................................................... .... ...... .... .. ...... 17 4.3 Projectile Lethality Testing- BRL-.... ............................................................ .. .... .. .... ..........._. 18 ACR Field Exp~riment ............. .......... .. .. .... ....... .... ........ .... .. .. .. .... ...... .............................................21 5.1 Test Integration Working Group - TIWG ............................. ...................................................21 5.2 Buckner Range ................. .... .... ................................. ........................................................ 22 5.3 Test Rationale and Design ..................................................................................................23 5.4 Field Experiment ....... .... .................................................................................................... 28 AMSAA Analysis ....................... ....................... .... .. .... .... ................. ........................ ......................3 3 6.1 Results of the Field Experiment .... .. .. ........................................................ ...... .. .. ........ ........33 6.2 Record Fire· ....................... ................................. ............. .... .. .. ..........................................33 6.3 Hit Performance .............. ...... ... ............................................................................. ............. 35 Program Ombudsman ...................................................................................................................41 7.1 Wetzel International ...........................................................................................................41 8.0 Conclusions .... ..................... .......... .................................. .................................. ............... ...........43 9. 0 References ....................... ............. .... .... .... .... ......................... .......... .... ....................... .. ........ .... ...4 7 Appendix A ACR Operational and Organizational Plan Appendix B Contractor Activity Synopsis Appendix C Program Planning Summaries Distribution List ~..-. ..•.•.•· ~ . , .I \ INTENTIONALLY LEFT BLANK Advanced Combat Rifle Program 1.0 INTRODUCTION. In April 1980 the United States Congress House Armed Services Committee requested that the Joint Service Small Arms Program (JSSAP) office conduct a study of the current combat rifle. This study concluded that the current rifle, the M16A 1, met all the U.S. Armed Forces needs but possible improvements to it should be investigated. A series of improvements have since led to the M16A2 and M16A3 rifles. For the long term, the study concluded that the technology -base should be developed to support a significant improvement in capability. Revolutionary improvements in capability were envisioned to be well beyond the year 2000, leaving the opportunity for a significantly improved combat rifle in the mid1990 time frame. A technology base effort was initiated. L.,...__ _ _ _ _..;___ _ _ _ _ _ __ __ _J Concurrent with initiation of the technology base efforts, the Honorable James Ambrose, then Under Secretary of the Army, saw the need to do something for the individual soldier. Through his encouragement and direction, the Advanced Combat Rifle (ACR) program was established. The ACR Operational and Organizational Plan (0&0) was approved in January 1985 and the program received his personal approval in February of the same year. The ACR effort caused weapon concepts to be developed under contract and prototype hardware to be produced and evaluated with troops in a field experiment. The prog·ram remained a technology base activity. The program was concluded upon completion of the field experiment in 1990. The program has significantly advanced the state-of-the-art in rifle technology and will form the basis of any future individual weapon requirement. 1.1 Description of Systems. Concepts were developed under contract to improve the soldier's hit performance in combat. Under the stress of combat where there are multiple targets, moving targets, and targets that are mostly obscured and exposed for short amounts of time, the soldier's performance is degraded. When the soldier does engage these targets, he does so hurriedly and with large aiming errors. The weapon concepts were developed to fire more than one projectile pertrigger pull. The dispersion ofthis burst of projectiles was controlled to compensate for the soldier's aiming error. ... ·- ,;-:;···- ,.. _ , _ ~~~ __ Page 1 The following is a brief description of the weapon systems taken to the field experiment. A synopsis of system char~cterist ics is given in Figure 3.1 on page 9. AAI Corporation - 5.56 mm serial launch salvo rifle, reciprocating bolt action, · firing brass cased flechette ammunition. Colt's Manufacturing Co. - 5.56 mm serial launch salvo rifle , reciprocating bolt action, firing brass cased duplex ball ammunition. 1.2 Heckler & Koch - 4.92 mm serial launch salvo rifle, rotating chamber action, · firing caseless ball ammunition. Steyr-Mannlicher- 5.56 mm serial launch salvo rifle, rising chamber action, firing telescoped plastic cased flechette ammunition. Program Goals and Objectives. As outlined in the ACR 0&0 Plan (see Appendix A), the ACR will be the initial development within the small arms fam ily. It will q_e the primary weapon for the individual soldier. Primary target will be the individual threat soldier protected by body armor at ranges out to 600 meters. It must offer enhancement in hit probability of at least 100 percent at combat ranges over the baseline performance of the M16A2 rifle when measured under real istic battlefield conditions. At extended ranges, the improvement required will be considerably greater than 100 percent. The weapon will be expected to enable th~ rifleman to detect targets at ranges greater than 400 meters in offensive action and at least 1000 meters during conduct of the defense. Acquisition and engagement of the target is expected to occur at 400 meters during offense and 600 meters during defense. . Page 2 • • "';... • • • • .•~ " .. . •••ot · ~~ ~ .· --~. : ," 2.0 BACKGROUND. An analysis of current small arms (e.g. hand held individual weapons) considers the man/machine interface to be a significant factor affecting system performance. While most systems offer excellent accuracy, the soldier's ability to hit targets depends on his situation. Figure 2.1 is a graph showing the probability of hitting a kneeling man size target as a function of range . The top curve labeled "M16A2 Capability" represents the capability of the weapon system in a fixed mount. The hit probability is decreased at the longer ranges due to the round to round dispersion of the ammunition which is about .275 mils. The second curve labeled "M16A2 Training" represents an aiming error of 1 mil and is representative of a training standard. It is the performance achieved in the Army record fire program. Marksmanship and zeroing performance is better than this and represents an aiming error of about .5 mils. The soldiers performance in an operational environment however, is worse than the training standard. Where targets are obscured, mostly moving and exposed for short amounts of time, studies have shown performance to be significantly worse. The bottom curve labeled "M16A2 Stressed" is derived from a large data base of tests involving moving and short time of exposure targets. AMSAA reviewed this data and used the worst third of the d_ata to represent the expected soldier's performance in a stressed environment. This does not represent actual combat stress, but was used as the basis for the ACR program. ACR HIT PROBABILITY GOAL 1 .0 :1 0.8 - :X: a. >- 0.6 ~ :s ~ ,g ... 0 - a.. 0 .4 :I: 0.2 M1 6A2 STRESSEDD--------------------~========~ 0.0 0 100 200 300 400 Range ( Meters) 500 600 700 Figure 2.1 At very close ranges of 0-1 00 meters aiming errors were assumed to range from 8-1 0 mils. These targets are exposed for very short amounts oftime and are hurriedly engaged, often Page 3 by pointed fire rather than aimed fire. At ranges of 300-400 meters the aiming errors drop to about 3 mils, and at extended ranges from 500-600 meters aiming errors of 1-2 mils were expected. The technical challenge in the design of an ACR concept was to compensate for or reduce these large aiming errors, and thus significantly improve combat effectiveness. Analysis has shown that for these aiming errors, if a salvo ofthree projectiles is fired at a target the probability of at least one hitting the target could be 1 increased on the order of 100%. There are two types of salvo launches. A true salvo system launches multiple projectiles at one time. The projectiles are distributed about the aim point as shown in Figure 2.2. A burst POINT OF extreme spread of 6 mils is optimal for this system for AIM the aiming errors assumed. McDonnell Douglas was developing a true salvo system of this type launching multiple flechettes for each round fired . This system :ALVO FIRE BURST PATTERN was not taken into the field experiment due to technical Figure 2.2 difficulties. The other multiple launch systems are those' L - - - - - - - - - - - - - - - . 1 that launch the-projectiles serially, or one behind the . other as shown in Figure 2.3. These can be in the form of a duplex cartridge like that developed for the Colt system, or they can be a burst of more than one round. Optimum burst extreme spread for these systems is 8 mils. This will also result in a 100% increase in hit probability over the stressed hit curve. The extreme spreads for systems other than the duplex (like those of AAI, H&K and Steyr) are difficult to obtain. High cyclic rates within the burst are generally requ ired, as is the addition of muzzle compensation and the use of low impulse ammunition, such as flechettes . The H&K system did not use low impulse ammunition, but relied on a unique mechanism for controlling its recoil. 2.1 History. The technology base efforts that were initiated in the early 1980's as a result of the Combat Rifle Study focused on the potential of salvo weapons, caseless ammunition, and optic sights. Requests for proposals to develop and demonstrate such systems were released. In 1982 the Under Secretary of .the Army endorsed a potential1 0-12 year rifle development program and requested that two such development contracts be awarded in lieu of the pia~ ned single award. 2 POINT OF AIM SERIALLY FIRED BURST PATTERN Figure 2.3 In Sept 1982 contracts were awarded to AAI Corporation and Heckler and Koch, Inc. The AAI effort was later terminated due to technical difficulties encountered. A summary of these and all contract efforts can be found in Appendix B of this report. Page 4 ~ -~·): . -·~ . •""' .. j _, During the next few years the Under Secretary continued to press for an accelerated program with additional industry involvement. In 1984 the ACR program evolved. The Operational and Organizational Plan was staffed and approved in January 1985. A program strategy was approved by the Under Secretary in February 1985. This strategy called for additional industry involvement and the demonstration of potential technology in a field experiment with troops. The thrust of the program direction from Mr. Ambrose was to challenge industry based on the need defined in the 0&0 Plan, to focus on current technology, and to demonstrate this technology to the user as a "stake in the ground" to form the basis of a possible requirements document. The approved acquisition strategy was one of the first in the "ASAP" Accelerated Acquisition Process which planned four years to production from the generation of a requirement document. In 1984-1985 industry conferences were held at ARDEC and Ft. Benning to detail the needs and goals of the program. Shortly thereafter, contracts were competitively awarded to AAI, ARES, Colt, McDonnell Douglas, and Steyr. These contracts cam~ to be known as the industry alternative efforts. These efforts called for the development and fabrication of the proposed rifle systems for evaluation in government tests. The contracts were phased with no commitment on the part of the government to proceed into the next phase. The phase I effort required the development of a test fixture that would demonstrate the potential of the system. Phase II was the development and testing of one weapon system , wh ile the final phase Ill effort called for the production of hardware for testing. The ongoing H&K contract was modified to include a hardware production phase to bring it into line with the other contracts. The ARES and McDonnell Douglas contracts were terminated at the end of their phase II effort due to lack of maturity of their systems. A complete chronology outline of the ACR program is provided on the following pages. OGA Support. The delivered weapon systems were evaluated by several government 2.2 agencies both with and without contractor support. Combat System Test Activity (CSTA) : Initial evaluation of the weapons' function and safety was conducted as well as several eng inee ring tests to assess the maturity of the systems. Test and Evaluation Command (TECOM) : Provided the safety release to allow the firing of the weapons by troops. Safety release was based on CSTA testing. Ballistic Research Laboratory (BRL): Tested all the ACR concepts against tissue simulant gelatin to assess the lethal characteristics of the projectiles. Tests provided information for the calculation of the indices of probability of incapacitation given a hit ; the projectile lethality. TEXCOM Infantry Board (INFBD) : The INFBD conducted the actual field experiment or troop test at Ft. Benning. Army Material System Analysis Activity (AMSAA): AMSAA performed the data analysis of the test results from the INFBD, CSTA and BRL tests. These efforts are discussed in detail in the remainder of this report. Page? ACR Program Chronology 1980 • JSSAP taskeQ by Congress to conduct Combat Rifle Study (CAS) to address : .1981 • Deficiencies of M16A 1 rifle Replacement candidates for M16A 1 rifle Requirements for a new combat rifle Results of CRS: Established stated service need for significantly/revolutionary improved rifle Near Term- Retain product improvement over M16A 1 Long Term- Develop technology base for ACR 1982 • • Under Secretary Army (USA) endorses rifle development program for 10-12 year technology approach Two competitive contracts awarded to AAI and Heckler & Koch to pursue the following technologies: - • Caseless Salvo Optics M16A2 Rifle Type Classified in November 1983 • USA requests acceleration of program and directs user to set performance goals and become more involved ~ 1984 • USA cal ls for vigorous program to acquire a significantly improved successor to the M16 rifle • TRADOC tasked to define requirements .• E~phasis placed on technology currently available • USA direction results in formu lation of industry alternative strategy • ACR Industry Conference Briefing; USAIS Ft. Benning, GA • Accelerated program approved by Army Materiel Command (AMC) • ACR Operational and Organizational (0&0) Plan drafted Page 6 · ) 1985 • "-1 0&0 Plan approved by Training and Doctrine Command (TRADOC) in January • USA approves ACR program and field experiment • AMSAA/BRL study concludes that the best way to 'improve rifle performance in near term is to fire multiple projectiles per trigger pull with a (controlled) salvo pattern of dispersion • Industry briefed on new alternative rifle program in May • RFP released in September 1986 • Industry Alternative Program awarded Phase I contracts to: - 1987 • AAI Corporation ARES Inc. Colt's Manufacturing Company Me Donnell Douglas Helicopter Company (MDHC). Steyr-Mannlicher Heckler & Koch (modification) MDHC & ARES efforts were terminated due to hardware immaturity • Test Integration Working Group (TIWG) chartered to design and plan ACR test program • Range instrument requirements identified 1988 • Test and Evaluation Master Plan (TEMP) drafted • HEL Salvo Stress Test conducted • Field experiment test design complete • Range instrumentation requirements initiated 1990 • Buckner Range completed • Hardware delivered • Safety and Engineering Tests conducted • ACR field experiment conducted • Lethality Test conducted 1991 • • AMSAA analysis conducted ACR Final Report prepared Page 7 l ·:r ·,·. INTENTIONALLY LEFT BLANK .. Page 8 3.0 ACA CANDIDATES - WEAPON SUMMARIES. 3.1 General. The ACR prototype weapon systems tested in the ACR field experiment were developed under contract by AAI, Colt, H& K, and Steyr. The ACR concept concentrated on developing a weapon system based upon available technologies in the areas of weapon, ammunition, and sight design. A synopsis of the weapon systems' characteristics is given below in Figure 3.1. SYSTEM CHARACTERISTICS AAI Colt H&K Steyr M1 6 A2 Standard Weapon Length (inches) 40.00 40.625 extended 36.75 retracted 29.53 30.12 39.63 Weapon Mechanism reciprocating bolt reciprocating bolt rotating chamber rising chamber - reciprocating bolt Weight (lbs.)* 9.39 10.30 9.15 (optic only) 8.53 8.80 Sights iron or 4x optic iron or 3.5x optic multi pwr optic 1.0x & 3.5x iron or multi pwr optic 1.5x & 3.5x iron only- 30 30 45 24 30 sem1-aummauc 3 round salvo burst sem1-aummanc automatic sem1-aummauc automatic 3 round salvo burst sem1-aulomauc 3 round salvo burst J rouna oursr Caliber (mm) 5.56 5.56 4.92 5.56 5.56 Cartridge brass cased flechette duplex & M855 ball caseless ball plastic cased flechette M855 ball Muzzle Device muzzle compensator muzzle brake compensator none flash suppressor flash suppressor Chamber Pressure (PSI) 55,000 50,750-M855 50,000-duplex 56,000 60,000 50,750 Muzzle Velocity (ft./sec.) 4,600 3,110-M855 2,900-duplex 3,000 4,900 3 ,1 10 Barrel Twist (inches) 1:85 1:7 1:6 1:100 1:7 Magazine Capacity (rounds) Modes of Fire (· • Weight includes iron and optic sights a11d l?aded magazine of ammunition. Figure 3.1 Page9 3.2 AAI. 3.2.1 Weapon. The AAI ACR (see Figure 3.2) is a gas operated, air-cooled, magazine fed. flechette firing rifle. It has the capability to fire either a single shot semiautomatically, ora high cyclic three round salvo burst using a thirty round magazine. The AAI ACR is a modification to the previously developed serial bullet rifle. It fires from the closed bolt position and utilizes a muzzle device that reduces barrel climb in the three round burst mode. The rifle uses either an interchangeable iron or optic sight. ;; Figure 3.2 3.2.2 Am m p n it i o n . STEEL The AAI ammunition (see FigFLECHETTE ure 3.3) consists of a 10~ 2 grain steel flechette using the standard M855 brass case. The projectile package includes the flechette projectile, a four segment sabot, and an "0-ring" "0.. RING used to hold the sabot segments PRIMER together. The sabot segments separate from the flechette afAAl FLECHETTE AMMUNITION termuzzleexitallowingtheflechFigure 3.3 ette to continue its a e r o d y n a m i c L - - - - - - - - - - - - - - - - - - - - - - - l flight downrange towards the target. The light weight projectile and high muzzle ve locity allows for a relatively flat trajectory over long ranges. Page 10 ,, '" 3.2.3 Sight. The AAI ACR uses either an iron or four power (4X) optic sight. A quick release lever allows the changeover without the need to rezero the weapon. The optic sight has a tritium powered reticle (see Figure 3.4) for ease .of use in reduced light level situations. The optic sight also incorporates aiming point stadia lines for 400, 500, and 600 meter ranges. Along the top of the rifle is a long aiming surface to assist in quick fire engagements. 3.3 rl Colt. AAI RETICLE PATTERN 3.3.1 · Weapon. The Colt ACR (see Figure Figure 3.4 3.5) is a human engineered derivative of the curre.nt M16A2 rifle. It uses the same operating mechanism used in the standard M16A2 and fires the standard 5.56mm M855 NATO round interchangeably with a newly developed duplex ammunition. It can fire either in the semi-automatic or full-automatic mode using a standard M16A 1 trigger mechanism. The rifle incorporates a newly designed handguard which consists of a heat resistant inner shield, air cooling vent holes, and a front end restricting ring. It offers a telescoping buttstock to cusfom fit the individual shooter. The rifle also has a muzzle oreak compensator (MBC) and a riew oil/spring hydraulic buffer to reduce recoil of the weapon. This weapon also has interchangeable iron and.optic sights. COLTACR t=igure 3.5 3.3.2 ., · ~·-· l~i:-1io>~ .), , • .......... Ammunition. The Colt ACR fires either the NATO standard M855 round or a newly developed 5.56mm duplex ammunition (see Figure 3.6). It is envisioned that this system would remain a two ammunition type family: one ammunition for short range (duplex) and a second for long range (M855). The duplex ammunition consists of two similar projectiles positioned nose to tail in the same cartridge case, in which the leading projectile will proceed to the weapon's aimppint while the trailing projectile will have some random dispersion around the aimpoint. This concept should improve the probability of at least one projectile hit fo r each round fired. lhe standard M855 round contains a single 62 grain projectile, while the duplex's front and rear projectiles weigh 35 and 33 grains, respectively. Page 11 • ·-~ ~ N855 PROPELLANT BED BRASS CASE COLT M855 AMMUNITION PROJECTILE WITH STEEL PENETRATOR PRIMER N855 BRASS CASE COLT DUPLEX AMMUNITION PRIUER STEEL CORED DUPLEX PROJECTILES .. Figure 3.6 3.3.3 Sight. The Colt ACR uses either a detachable iron sight or a 3.5 power optic sight. The iron sight includes the carrying handle and a flip-type aperture for both short and long range targets. The optic sight is equipped with a self-powered illuminating reticle pattern (see Figure 3.7) for periods of reduced light. The rifle also has an aiming/pointing rib on its upper surface for quick target engagements. 3.4 - •I- - -~ -~-- -~-- Heckler & Koch (H&K). 3.4.1 Weapon. The H&K ACR (see Figure COLT RETICLE PATTERN 3.8) is a gas operatea bullpup rifle firing caseless Figure 3.7 ammunition. The weapon operates using a rotating chamber mechanism and is charged with a rotary cocking device located on the side of the weapon. It can fire either semi-automatic, fullyautomatic, or a three round salvo burst using a forty-five round magazine. Its caseless ammunition eliminates the need for an extraction cycle during firing allowing its salvo burst to be fired at over 2,000 rounds a minute. Its operating mechanism is unique in that the recoil of the weapon is delayed until after the round(s) have left the muzzle. The H&K ACR only offers the use of a day optic. -;or, ...,-.- ·-.·-....-- Page 12 ·- · · - · - . . . . . ... . - ....... · - . ., H&KACR Figure 3.8 3.4.2 Am m u n it i o n . The ammunition is fully telescoped 4.92mm caseless ball ammunition (see Figure 3.9). This square cross section round consists of the nitramine based solid propellant body, a single 51 grain bullet projectile, primer, BOOSTER MIX IN COPPER booster and plastic end cap. All CUP ammunition components are H&K CASELESS AMMUNITION consumed during firing except Figure 3.9 for the plastic end cap and copper booster cup which exit the muzzle upon firing. This round also has a variety of coatings to provide additional waterproofing, low friction surfaces, and heat resistance. PROPELLANT BODY PLASTIC END CAP 3.4.3 Sight. The H&K ACR uses a muhipowered (1.0X or 3.5X) optic sight which is integrated into the rifle's carrying handle. There is no backup iron sight on this weapon. The magnification is adjusted by turning a ring located on the eyepiece which also has settings for 400, 500, and 600 meters. The optic's reticle pattern (see Figure 3.1 0) offers a stadia. line pattern that ,can be used to estimate distances beyond 300 meters. The magazine, which is located atop the weapon along the barrel, serves a secondary purpose of providing a pointing aid to the shooter for rapid engagement scenarios. I d~ H&KRETICLEPATTERN '• Figure 3 .~ 0 Page 13 3.5 Steyr. 3.5.1 Weapon . . The Steyr ACR (see Figure 3.11) concept is a novel bullpup style weapon featuring a rising chamber mechanism and a side initiating plastic cased round. The weapon can fire eitherasingleshotora three round high cyclic salvo burst. The weapon system and mechanism is very simple. It fires a flechette projectile from a twenty-four round transparent magazine. The Steyr ACR fires from the open bolt position in which a live round enters the chamber only after the trigger has been pulled. This characteristic greatly reduces the concern for ammunition cook-off. The iron sight is removab l ~ and interchangeable with the STEYRACR Fi ure 3.11 preferred day optic. STEEL FLECHETTE 3.5.2 Ammunition. The Steyr ACR ammunition (see Figure 3.12) consists of a fully telescoped plastic cased 9.85 grain fin stabilized flechette. The flechette/ sabot package is similar to PLASTIC that used in the AAI system . CASE The Steyr round utilizes aside initiating primer which Ignites STEYR FLECHETTE AMMUNITION using a fixed firing pin located .___________F_ig_u_re_3_.1_2_ _ _ _ _ _ _ ___, at the top of the chamber housing. The movement of the rising chamber creates the impact energy required to ignite the round. The Steyr flechette travels at a very high velocity which requires no elevation adjustmer)ts out to at least 600 meters. Pa~e 14 ·~ 3.5.3 Sight. The Steyr ACR uses either an iron peep sight or a multi-powered optic sight. All windage and elevation adjustments are made on the front sight post while using the iron sights. The optic incorporates a multi-powered (1.5X or 3.5X) magnification capability that can be adjusted with a simple twist of the eyepiece. The optic uses a ring reticle pattern (see Figure3.13) in which the shooter simply places the target inside the ring and fi res. There is also a long shotgun style rib/carrying handfe along the top surface of the rifle to aid as a pointing device in rapid target engagements. STEYR RETICLE PATTERN Figure 3.13 3.6 Summary. A detailed system description and in-depth contract summary is included in Appendix B of this volume. The weapon systems C?Perator and maintenance manuals are included in Volume Ill of this report. Contractor final reports are in Volume VII. Page 15 INTENT/ONALL Y LEFT BLANK Page 16 4.0 ENGINEERING TESTS. 4.1 Background. Prior to the ACR field experiment in 1990, safety and engineering tests were conducted at Aberdeen Proving Grounds (APG), Maryland, to assess the various ACR concepts. The U.S. Army Test and Evaluation Command (TECOM) issued an ACR safety release which was required to allow military personnel to participate in the field experiment. This safety release assigned specific limitations on each ACR concept based upon test information. The U.S. Army's Combat System Test Activity (CSTA) was responsible fqr conducting all ACR safety and engineering tests, while the Ballistic Research Laboratory (BRL) conducted live fire projectile lethality testing. 4.2 Safety and Engineering Tests - CSTA. 4.2.1 Objective. The objective of testing conducted by CST A was to determine whether the ACR candidates were safe for military personnel to operate and to demonstrate their technical performance. All live firing was conducted by the Light Weapons System Division of CST A's Armament System Directorate at APG. The test program at CSTA was designed in a three phase effort. Phase I was the safety qualification phase in which those tests required to issue a limited safety release would be performed first. The next two phases consisted of the ammunition and weapon technical feasibility tests. These tests were conducted to demonstrate 'the technical performance characteristics of the various ACR concepts. The testing was designed by CSTA in consultation with the ACR Test Integration Working Group (TIWG) and in conjunction with the Independent Evaluation Plan (IEP) prepared by the U.S. Army Material Systems Analysis Activity (AMSAA). .!- 4.2.2 Description of Tests Performed. The safety qualification testing of the ACR candidates included weapon inspection, reliability; cook-off, toxic fumes, system signature and projectile hazard subtests. The ammunition feasibility test plan examined thermal shock, waterproofness, salt-fog, penetration, exterior ballistics and chemical compatibility. The weapon phase of this testing evaluated accuracy/dispersion characteristics,·extreme temperature performance (high and low temperature), accessory compatibility and an engineering study. A human factors summary was conducted to determine the human engineering characteristics of the ACR candidate weapon systems. The ·Human Engineering Laboratory (HEL) at APG provided support and assistance to CSTA regarding the human factors engineering aspects of the ACRs. Due to funding limitations and the engineering status of the ACR prototype hardware, the original test schedule was modified to include only.those tests required and/or considered of significant importance to the program. 4.2.3 Su~mary Results. The result of the CSTA safety qualification testing was a recommendation to TECOM for a limited safety release so that these prototype weapons could be fired by military personnel in the 1990 field experiment. The safety release was continuously updated as testing at CSTA continued. Several amendments to the TECOM safety release were issued throughout the field experiment. General restriction outlined in the safety release included: weapon handling, hearing protection, weapon/ammunition compatibility, and maximum round limitations. There were also specific restrictions placed on each of the ACR candidates which inc!uded: firing limits without cooling (cook-off concern), ammunition and weapon safety characteristic;s, and system specific maintenance and safety procedures. The Page 17 most critical element concerning the various safety release amendments involved the Steyr ACR system. Safety concerns involving ruptured buttstocks caused the Steyr system to be temporarily removed from testing and very stringent maintenance requirements to be placed on the contractor to allow the Steyr ACR to be further tested in the fie ld experiment. .> A complete detailed description and summary of testing and test results can be found in CSTA report#USACSTA 7103, TECOM Project No. 2-WE-600-ACR-001, "Final Report : Technicai .Feasibility Test of Advanced Combat Rifle Candidates," 1992. 4.3 Projectile Lethality Testing- BRL. . 4.3.1 Objective. The objective of the BRL testing was to estimate, assess and test the lethality capabilities of the various ACR projectiles. BRL was responsible for deriving