Historical Document · 1968
A Ballistic Research Laboratories report of February 1968 (declassified) comparing the SPIW's modes of fire. The Hyper-Burst Mechanisms dive cites it for the measured value of controlled bursts.
UNCLASSIFIED AD NUMBER AD388522 CLASSIFICATION CHANGES TO: unclassified FROM: confidential LIMITATION CHANGES TO: Approved for public release, distribution unlimited FROM: Distribution: No Foreign AUTHORITY Group 4 per document markings; USARRDC Ltr., 8 Mar 1978 THIS PAGE IS UNCLASSIFIED CONFIDENTIAL TTHIS W COPY T CONSISTS OFJ 2iPAGES F 15COPIES, SERIESA. 1AD MEMORANDUM REPORT NO. 1864 SPIW MODES OF FIRE (U) 030 by i -4W. Hall, Jr. William W. Sheldon W. Meade Werner Emma M. Wineholt ) hiAR 2819 .. February 1%8 In addicion to security requirements which must be met, this document is subject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of Comnanding Officer, U.S. Arny Ballistic Research Laboratories, Aberdeen Proving Ground, Maryland IBALUSTIC RESEARCH LABORATORIES S. ARMY MATERIEL COMMAND U. ABERDEEN PROVING GROUND, MARYLAND GROUP-4 DOWNGRADED AT 3 YEAR INTERVALS DECLASSIFIED AFTER 12 YEARS C0O4IDENTfI~IAL A.7 When this report is no longer needed, Department of the Army organizations will destroy it ih accordance with the procedures given in AR 380-5. Navy and Air Fcrce elements will destroy it in accordance with applicable directives. Department of Defense contractors will destr9y the report according to the requirements of Section 14 of the Industrial Security Manual for Safeguarding All others will return the report to Classified Information. Ballistic Research Laboratories, Aberdeen Proving Ground, Maryland. This document contain information affecting the national defense of the United States within the meaning o the Espionage Laws, Title 18 U. S. C. Sections 793 and794. The trammissionorthe revelation of its contents in any manner to an unauthorised person ts prohibited by law. The findings in this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents. CONFIDENTIAL RESEARCH BALLISTIC LABORATORIES MEMORANDUM REPORT NO. 1864 FEBRUARY 1968 SPIW MODES OF FIRE (U) Fred W. flall, Major, OrdC William W. Sheldon, Major, Inf W. Meade We er Emma M. Wineolt Interior Ballistics Laboratory In addition to security requirements which must be met, this document is subject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of Commanding Officer. U.S. Army Ballistic Research Laboratories, I -"Is Aberdeen Proving Ground. Maryland tefe!.5e Of t"' . , .'. ".Z -Mu..d: i. i' ..'.. 7, its contents o~ Its In anY manaer to w± ua&J2o1 ed 794. 1 irfoO irsproXoa is pra"ibitet by law.' RIT&E Project No. 1X542703D345 ABERDEEN PROVING GROUND, MARYLAND The following page is blank. CONFIDENTIAL t BALLISTIC RESEARCH LABORATORIES MEMORANDUM REPORT NO. 1864 FWHall, Jr./WWSheldon/ WMWerner/EMWineholt/sjw Aberdeen Proving Ground, Md. February 1968 SPIW MODES OF FIRE (U) (UNCLASSIFIED) ABSTRACT A study was made to investigate the most effective mode of aimed fire to engage linear and point targets with the rifle portion of the Special Purpose Individual Weapon (SPIW) system. Basic test data were generated by a group of riflemen firing a total of approximately 23,000 rounds at different types of simulated targets on the range facilities at Fort Benning, Georgia. A supplementary phase discussed in this report is the applicability to the SPIW of doctrine evolved for full automatic fire from other rifle systems. 3 The following page is blank. TABLE OF CONTENTS (UNCLASSIFIED) Page ABSTRACT . . . . . LIST OF ILLUSTRATIONS 3 7 ................... LIST OF TABLES . . . . . . . . . . . . . . . . . . LIST OF SYMBOLS . . . ..................... GLOSSARY . . . . e . . I. INTRODUCTION . . . . . . . . . . . 13 . . . . . . 14 ........................ . . ....... .... SUMMARY OF PRESENT DOCTRINE III. TEST PLAN IV. TEST RESULTS............ . . . . . . . . ...... V. TEST RESULTS AND PRESENT DOCTRINE .... VI. 15 ....................... II. . . . . . . 11 . .. . . 17 ........................ 19 . ........................ 21 ............. ... 35 ............ ....................... 37 A - FACILITIES ........ ......................... 41 B - PROCEDURES ........ ...................... . .. 47 .................... ... 65 CONCLUSIONS APPENDIXES C -TABLES D- OF DATA ....... TARGET PHOTOGRAPHS ............... DISTRIBUTION LIST ........ . ... 115 ..................... .157 The following page is blank. , 1 I (UNCLASSIFIED) LIST OF ILLUSTRATIONS Figure Page 1 Controlled burst, point target, standing, Firer No. 1 . 2 Full automatic, point target, standing, Firer No. 1 . . . 23 3 4 Controlled burst, sweep target, standing, Firer No. 1 . . 23 Full automatic, sweep target, standing, Firer No. 1 . . . 24 5 Controlled burst, sweep target, standing, one trial of Firers 1 through 5 6 . . . . . . . . . . . 23 . 26 . Full automatic, sweep target, standing, one trial of Firers 1 through 5 .................. 26 . . . . . 27 7 Controlled burst, calibration target, 8 Controlled burst, sweep target, standing 9 Full automatic, sweep target, standing 10 Controlled burst, point target, standing 11 Full automatic, point target, standing 12 Target area projected onto a target panel . . . . 13 Zone of consideration, sweep target computer simulation . 30 14 Ratio of hit probability, full automatic to controlled burst versus range 15 * # . * . .. standing . 28 * * * . . .. . . . 0 . . . . . 28 . . . . . . 28 . . . . . . . . . . 28 . . ... . . . . 29 . . . . 31 . Ratio of the projectile impacts within the target area versus range, full-automatic to controlled-burst modes . . . . . . ..... . .. ..................... .41 ................. 1A Verification test range ..... 2A Sample target. 3A 4A .................. .. Pseudo-tactical range .. Silhouette target array . ................. 5A Pseudo-tactical firing position .... 6A AAIC weapon IB Calibration target ................... 28 3B Sweep target 4B Standing posit 5B Prone position ..... . . 33 . . . .. 42 ..................... 43 .43 ............. .44 ....................... . . . . . . 47 .. . . . . . . . . . Point target.. 45 . ion....... . . . . . 48 .. ......................... 48 ............. 51 6B .... . ..................... Supported position ..... .. .................... 7B Layout of Tables IV through VIII . . . . . . . . . . . .61 88 Layout of Tables IX through XIII . . . . . 7 . . . . 52 55 . .62 LIST OF ILLUSTRATIONS (Continued) Figure Page ID 2D Calibration, controlled burst, standing, Firer No. 1 . . 117 Calibration, controlled burst, standing, Firer No. 2 . . 117 3D Calibration, controlled burst, standing, Firer No. 3 . . 118 4D Calibration, 5D Calibration, controlled burst, standing, Firer No. 5 . 6D Calibration, controlled burst, standing, Firer No. 6 . . 119 7D Calibration, controlled burst, 8D Calibration, controlled burst, standing, Firer No. 8 . . 120 9D Calibration, controlled burst, standing, Firer No. 9 . . 121 10D Calibration, lD Calibration, controlled burst, standing, Firer No. 11 • 122 12D Controlled burst, sweep target, standing, Firer No. 1 . 122 13D Controlled burst, sweep target, standing, Firer No. 2 • 123 14D Controlled burst, sweep target, standing, - 1V 15D Controlled burst, sweep target, standing, Firer No. 4 . 16D Controlled burst, sweep target, standing, Firer No. 5 • 121, 17D Controlled burst, sweep target, standing, Firer No. 6 . 18D controlled burst, standing, Firer No. 4 . . 118 standing, . 119 7 • . 120 Firer No. controlled burst, standing, Firer No. 10 Firer No. . 3 121 124 125 Controlled burst, sweep target, standing, Firer No. 7 • 125 19D Controlled burst, sweep target, standing, Firer No. 8 . 126 2011 Controlled burst, sweep target, standing, Firer No. 9 • 126 21D Controlled burst, sweep target, standing, Firer No. 10 . 127 22D Controlled burst, sweep target, standing, Firer No. 11 . 127 23D Full automatic, sweep target, standing, Firer No. 1 . . 128 24D Full automatic, sweep target, standing, Firer No. 2 . . 128 25D Full automatic, sweep target, standing, Firer No. 3 . . 26D Full automatic, sweep target, standing, Firer No. 4 • • 129 27D Full automatic, . • 130 28D Full automatic, sweep target, 6 • . 29D Ful automatic, sweep target, standing, Firer No. 7 . • 131 30D Full automatic, sweep target, standing, Firer No. 8 • • 131 31D Full automatic, . . 132 sweep target, standing, Firer No. 5 standing, Firer No. sweep target, standing, Firer No. 9 8 129 130 LIST OF ILLUSTRATIONS (Continued) Figure Page 32D Full automatic, sweep target, standing, Firer No. 10 33D 34D. Full automatic, sweep target, standing, Firer No. 11 . • 133 Controlled burst, point target, standing, Firer No. 1 . . 134 35D Controlled burst, point target, standing, Firer No. 2 . . 135 36D Controlled burst, point target, standing, Firer No. 3 . • 136 371 39D 40D Controlled burst, point target, standing, Firer No. 4 . . 137 Controlled burst, point target, standing, Firer No. 5 . • 138 Controlled burst, point target, standing, Firer No. 6 . . 139 Controlled burst, point target, standing, Firer No. 7 . . 140 41D 42D Controlled burst, point target, standing, Firer No. 8 . . 141 Controlled burst, point target, standing, Firer No. 9 . . 142 43D Controlled burst, point target, standing, Firer No. 10 Controlled burst, point target, standing, Firer No. 11 38D 44D 45D 4 6D 4TD 48D 49D 50D 51D 52D 53D 54D 55D . . 132 . 143 . 144 Full automatic, point target, standing, Firer No. 1 . . . 145 Full automatic, point target, standing, Firer No. 2 . . . 146 Full automatic, point target, standing, Firer No. 3 . . . 147 Fulo automatic, point target, standing, Firer No. 4 . . . 148 Full automatic, point target, standing, Firer No. 5 . . . 149 Full automatic, point target, standing, Firer No. 6 . . .150 Full automatic, point target, standing, Firer No. 7 . Full automatic, point target, standing, Firer No. 8 . . . 151 . . 152 Full automatic, point target, standing, Firer No. 9 . . . 153 Full automatic, point target, standing, Firer No. 10 . . 154 Full automatic, point target, standing, Firer No. 11 . . 155 The following page is blank. 9 (UNCLASSIFIED) LIST OF TABLES Page I. Percentqe of Multiple Hits Versus Range . . . . . I. Pseudo-Tactical Sumary Sheet III, ..... . 32 .... 34 ........ Ammunition Data 46 IV. Miss Distance, Calibration, Standing . . . . . . 67 . V. Miss Distance, Sweep, Controlled Burst, Standing . . . . . 71 . . . . 75 VII. Miss Distance, Point, Controlled Burst, Standing . . . . . 79 VIII. Miss Distance, Point, Full Automatio, Standing . . VI. Miss Distance, Sweep, Full Automatic, Standing . TX. Measures of Dispersion, Calibration, Standing . 83 # * . . * . .* * X. Measures of Dispersion, Sweep, Controlled Burst, Standing . . * * . * . . . s . * . .. . .. * 89 . 91 XI. Measures of Dispersion, Sweep, Full Automatic, Standing XII. Measures of Dispersion, Point, Controlled Burst, Standing . . . .. * * 0.......... .. ..... . 93 XIII. Measures of Dispersion, Point, Full Automatic, Standing . 95 XIV. Summary Across Men, Measures of Dispersion . ...... XV. Extreme Spread, Calibration, Controlled Burst, .. XVI. XVII. XVIII. XIX. XX. 97 ... 98 Extreme Spread, Three-Round Burst, Low and High Rate of Fire, Standing, March 1967 . . . . . . . . * . . . . . . 99 Extreme Spread, Three-Round Burst, Low Rate of Fire, . Standing, March 1967, Individual Burst .. 100 Standing, November 1966 . ...... ..... Extreme Spread, Three-Round Burst, High Rate of Fire, Standing, March 1967, Individual Burst . . . . 101 . Co-ordinates, Three-Round Burst, Low Rate of Fire, Standing, March 1967 . . . . . . . . . . ........ . 102 Co-ordinates, Three-Round Burst, High Rate of Fire, Standing, March 1967 104 ............. XXI. Verification Test, Impacts Within the Zone of Consideration ..... . . . .................... XXII. Verification Test, Multiple Hits Versus Range XXIII. Trigger-Pull Rate by Individual and Test Condition (Trigger Pulls Per Second) ..... ............ if 87 21 . . . . 106 . . . . 107 108 LIST OF TABLES (Continued) Page XXIV. Pseudo-Tactical Test Data, Controlled Burst, Standing XXV. Pseudo-Tactical Test Data, Trigger-Manipulated Burst, Standing ........ ....................... ... 11 XXVI. Pseudo-Tactical Test Data, Full Automatic Extended Burst, Standing ........ .................... 12 . . . 109 113 (UNCLASSIFIED) LIST OF SYMBOLS -' i denotes the round number within a burst--- P 3 denotes the burst number (a three-digit number) m denotes the firer number ES denotes extreme spread H horizontal coordinate of an impact point N denotes the number of rounds in the jth burst S standard deviation of an individual measurement V vertical coordinate of an impact point Vi vertical coordinate for the ith round of the jth burst a averaged values of standard deviations, S 13 (UNCLASSIFIED) GLOSSARY SAWS - Small Arms Weapons Systems SpIw - Special Purpose Individual Weapon CB - Controlled Burst - Trigger manipulated burst of fil11 automatic fire FA - extended burst of full automatic fire S - Standing ::AL- Calibration SW - Sweep PT - Point spin - shots per minute successful trigger pull - at least one hit per trigger pull beaten zone - the area where a burst of automatic fire strikes the ground seconds of engagement - time recorded from the first to last shot of each trial rate-of-fire - natural cyclic rate-of-fire of a ,particular weapon mechanism (shots per minute) Tactical rate-of-fire Sustained rate-of-fire - average number of rounds expended per minute during an engagement of a target array (rounds per minute) - rate at which weapon inn fire indefinitely without seriously overheating 14 lit CONFIDENTIAL (CONFImqTIAL) I. INTRODUETION The Special Purpose Individual Weapon (SPIW) Research and Development " program is developing of automatic fire: a rifle that can be fired in three different modes controlled burst, trigger-manipulated burst and the extended full-automatic burst. The controlled burst consists of three rounds fired at an approximate rate of 2000 shots per minute; the number of rounds fired per burst is limited by the mechanism. For the purpose 'I of this report, the trigger-manipulated burst, by definition, contains two to five rounds; whereas, the extended full-automatic burst is more than five rounds. Both the trigger-manipulated and extended full-automatic bursts are fired at an approximate rate of 450 shots per minute and the rifleman can limit the number of rounds fired per burst. Early in 1966, the Ballistic Research Laboratories (BRL) conducted a pilot study of the motion of man and weapon during automatic fire from * the shoulder. The purpose of that investigation was to determine the rate-of-fire at which weapons of a low level of recoil impulse could be held on target during an extended burst in fUll-automatic fire of at least 10 rounds per trigger pull. The dispersion patterns obtained in extended, low rate-of-fire bursts were compared to patterns obtained by rapidly triggering, controlled bursts of three rounds per trigger pull at a high rate-of-fire. It was shown that the vertical dispersions of the two modes of fire were comparable. Thus, if the controlled-burst mode proved to be comparable in overall effectiveness and could fulfill the tasks normally assigned to the full-automatic mode, then the full automatic requirement could be eliminated. This would reduce the mechanical complexity of the trigger assembly and thereby increase the reliability of the mechanism. It i s pZanned to pubZish the results of this study in a separate report. 15 CONFIDENTIAL CONFIDENTIAL Results of the BRL study and a paper b§ Mr. Charles Rhoades of the Project Manager, Rifles Office, were presented at the SPIW Executive Coumittee meeting held on 13 October 1966. Mr. Rhoades listed various combinations of modes which could be incorporated in the SPIW point fire rifle. While discussing relative merits of the possible combinations, Mr. Rhoades emphasized that although the inclusion of controlled-burst, full-automatic and semi-automatic modes of fire seemed to be the most effective, there was some doubt that elimination of the full-automatic mode would result in a loss in overall effectiveness. In view of the results indicated by the pilot study, BRL was asked by the Project Manager, Rifles to design and conduct a test which would compare the relative hit capability of the controlled-burst versus fullautomatic modes of fire. The task was accepted and on 26 October 1966, a cub-committee consisting of representatives from the U.S. Army Infantry Board (USAIB), TECOM Headquarters, Frankford Arsenal, Combat Developments Command Infantry Agency (CDCIA), and BRL met to discuss the test plan. The test was carried out by BRL with the assistance of the USAIB at Fort Benning, Georgia during the period 14 to 23 November 1966. One of the authors, who is an experienced Infantry Officer, reviewed military tasks normally assigned to the full-automatic mode for Automatic Rifles. His survey was to confirm the adequacy of the basic test plan (Section III, following) for the comparison of the modes of fire and to provide the beds for analysis of the test results. Field test facilities are described in Appendix A. Included in the present report are: * A presentation of the results of the "Comparison of Modes of Fire Test" * A review of the tasks presently assigned to full-automatic fire Minutes of the Combined SPIW Executive Committee and lhdustry Meeting 12-13 October 1966. Fort Penning, Georgia. 16 CONFIDENTIAL CONFIDENTIAL 9 An analysis of the data in terms of present doctrine * A comparison of target area coverage * Data and computations which can assist in establishing military characteristics for rifles capable of firing a controlled burst. (UNCLASSIFIED) II. SUMMARY OF PRESENT DOCTRINE We initially determined what "application of fire" doctrine could Because the SPIW is a developmental item, be used in the analysis. current doctrine has not been revised to reflect any specific or general characteristics of the weapon. Automatic Rifle, Doctrine pertaining to the Browning MK1A2 Automatic Rifle, and M16AI Rifle was examined to see if it could be applied to the SPIW. A. Assumptions The following assumptions were made to define the limits of the discussion: 0 The dispersion characteristics of the present SPIW hardware will not change. * This weapon will be employed in the Automatic Rifle role. * There will be a companion automatic weapon for long-range automatic fire. * The sustained rate-of-fire, when established, will provide a volume of fire comparable to that available from the standard Automatic Rifle. B. Source of Information Doctrine of fire data were obtained from Department of the Army Field Manuals (DA FM). The primary sources of doctrine were DA FM's 23-12 and 23-16 pertaining to the employment and marksmanship of the Automatic Rifle. Other sources were the DA FM's pertaining to the combat in forti- fied and built-up areas, operations. patrolling, and desert, northern, and mountain These sources were checked for possible doctrine which might amplify or restrict the doctrine contained in the two primary sources. No amplification or restriction was found. 17 CONFIDENTIAL C. Combat Conditions 1. Targets. The following is a list of conditions under which com- bat targets occur on the battlefield. * The enemy is * Most targets are linear in nature and consist of men sAd objects irregularly spaced along covered and concealed areas. • Most targets can be detected by smoke, flash, dust, noise, or movement and will be visible momentarily. a The range to individual personnel targets rarely will exceed 300 meters. 4 2. seldom visible except during his assault. Engagement Conditions. The fire of a rifle squad in combat is directed under the following conditions: D. * Squad members are under stress caused by fear, fatigue, hardship, and battlefield noise. • Squad members do not limit their fire to clearly defined enemy, but also fire into clumps of brush, dark shadows, and other likely enemy locations. Present Doctrine The doctrine states that automatic fire is employed to obtain fire superiority and to engage enemy formations, large point targets, and automatic weapons out to a range of 460 meters. volume and accuracy of fire. Emphasis is placed on To insure minimum dispersion, Automatic Riflemen are taught to fire bursts of two or three rounds by means of trigger manipulation (TM). Present doctrine does not include extended bursts of full automatic (FA) fire. For the application of fire, enemy personnel targets are categorized 3 linear, column, point and area targets. The column is a special case f the linear target and is listed separately because its vertical nature requires a particular method of engagement. The applications of automatic fir-. to these targets are presented on the following page. 18 I 1. I !get * * Linear. The Automatic Riflmn fire burst. of two or three rounds, distributing their fire from the center to just outside the known flanks and back to the center. Column. The Automatic Riflemen fire in three-to-five round bursts at the center of the target but do not distribute their fire. The beaten zone of the Automatic Rifles is intended to adequately cover the target. t Point. The Automatic Riflemen fire in three-to-five round bursts at targets such as crew-served weapons or small groups of personnel. Automatic fire is used in order to take advantage of the larger beaten apne. 2. e Area. The Automatic Riflemen fire in three-to-five round bursts and distribute their fire in width ane' depth within their assigned sectors. T of Fire Doctrine also states the employment of Automatic lifle fire for the following situations. e Day Assault. The Automatic Riflemen fire in short bursts of two or three rounds from the underarm position at known or suspected enemy locations giving priority to enemy automatic weapons. Night Assault. The Automatic Riflemen fire a s.±ort burst of two or three rounds from the underarm position every time the left foot strikes the ground. e Limited Visibility. The Automatic Riflemen fire in bursts of three-to-five rounds within their assigned sector. A heavy volume of fire is directed toward the muzzle-flash of enemy automatic weapons. (UNCLASSIFIED) III. TEST PLAN The test plan developed was titled "The Comparison of Modes of Fire Test." It was comprised of two major subtests: and a Pseudo-Tactical Test. A summary of the test plan is presented here with a detailed description given in Appendix B. 19 I a Verification Test A. Summsr 1. Test Vlan Subtest I: a. Verification Test. Purpose This test was to determine if rapidly triggered, the vertical dispersion of controlled bursts is of extended bursts of low-rate, b. comparable to that full-automatic fire. Target A horizontal line was displayed on a 4 x 8-foot panel to represent linear targets and crosses for point targets. These basic targets were considered to be the type of targets most often engaged with automatic fire from a rifle at the shoulder. The distance from the firers to the panel was 500 inches. 2. Subtest II. a. Pseudo-Tactical Test. Purpose This test was to determine which mode of fire enabled the average subject to engage and hit the greatest number of point targets when a time stress factor is introduced. The successive engagement of a series of point targets was the procedure used. b. Target e Ten, M-type, pop-up, silhouette targets were positioned 10 meters apart at a 100-meter range. The nominal exposure time was 6 seconds. c. General In this subtest the trigger-manipulated, two-to-four round burst was added to provide data conforming to present doctrine. *A eilhouette of a standing man. 20 CONFIDENTIAL B. Limitations In addition to the requirements arising from doctrine and the desir- ability for conducting this test in the shortest possible time, with the least expenditure of funds, the following limitations applied to our investigations. 1. Because of the lack of tracers, any choice between modes of fire which depends on tracer mix or upon the presence of tracers, could not be addressed. 2. Because of the limited signature per round, any method of fire utilizing such information could not be addressed. 3. Because of the inability to realistically recreate tactical situations, the pseudo-tactical tests were therefore designed to force the subject to engage in motions which would be required during tactical situations. 4. Because amuunition was in short supply, each test routine had to be designed so that a malfunction or human error would not negate the entire sub-routine. C. Selection of Riflemen The 11 riflemen used for the test were selected from the group used during the SPIW Engineering Design Test (EDT) conducted by the U.S. Army Infantry Board. Each subject had fired over 2000 rounds from the SPIW and was considered to be thoroughly trained with the weapon. (CONFIDENTIAL) IV. TEST RESULTS A summary and limited discussion of the test results is presented. It is anticipated that these data and computations will be included in a larger study to assist in establishing the military characteristics for rifles capable of firing a controlled burst. A detailed tabulation of the raw data and various quantities calculated is contained in Appendix C. 21 CONFIDENTIAL yI .CONFIDENTIAL The data generated during the test while firing from the prone or supported position are not included. An analysis of these data indicates that the combination of weapon support, rate of fire, muszle compensation, and the light-weight flexible barrel adversely affected the dispersions obtained with the controlled-burst mode of fire. These results definitely erphasize the requirement for a more rigid barrel. The dispersion patterns obtained with the rifle when firing from the standing position are reasonably characteristic of what can be expected. The AAIC weapon used in this test was tuned for a right-handed rifleman to be fired from the standing position. is hoped to present a detailed dynamic analysis It of the rifle in a later report on the SPIW prototypea of 1966. A. Verification Test Results 1. Overplots. For each test condition a summary plot was prepared of all impact points on the panel so that visual comparisons could be made of target coverage and the magnitude of dispersion obtained each mode of fire. deviation (O'v) ith The average vertical miss distance (V) and standard are shown with each overplot. The results for a single firer (Firer No. 1) in the controlled-burst against a point target, are presented in and extended burst modes, Figures 1 and 2. Similar results against a sweep-type target are pre- sented in Figures 3 and 4. Five trials of 12 rounds each are represented in the overplots presented in Figures 1 through 4. Of an individual measurement. 22 CONFIDENTIAL ~ell ) (MtIS)(M V P-T. h '' - F A.. .....lT ...... .. .......... " ' S, .TO. -40 40O 3.1 ?0 -40 0 . mils or, ?0436 0 l MI I - . . ... Ir . i(Mils 5.S . .. l 1!) 23 Figure 3. Controlled-burst, swepta get, stndng Flr-ruto.tI -;>1 c'! S5 ; ,? il Figure 3. Controlled-burst, sweep target, standing, Firer No. 1 ' CONFIDENTIAL ('11, - A 01 41 ~I40 0'1 6.8 mils V V -0.7 mils Figure 4 (U). U Full-automatic, sweep target, standing, Firer No. 1 When each rifleman engaged :isweep-type target he was provided a magazine containing 12 rounds and instructed to commence firing on signal, using as his initial aim point the cross at the left end of the line. When fir.;.ng the contrclled-buxst mode he was to pull the trigger a total cff four times while attempting to fire at a rate of two to three trigger pulls per second. The plots do not distinguish the impact points of one trial from those of another; therefore, each of the four clusters pictured in Figure 3 consists of tbree impact points from each of the five trials. Thi:: target pattern represents the extreme case where the firer was consistent in sweep rate and trigger pull rate from one trial to the next; the controlled bursts struck the target in nearly the same location each time. Inspection of the target photographs presented in Appendix D reveals that, on the average, the riflemen were not as consistent from trial to trial as was Firer No. 1. When considering a single firer, coverage of the target region is different for the controlled-burst (CB) 24 CONFIDENTIAL L CONFIDENTIAL sweep conditio as compokred to the full-automatic (FA) sweep condition. For CB sweeping, the impact points are generally clustered with voids between the clusters. For FA sweeps the impact points are more uniformly spread out in the horizontal direction. The voids betveen clusters are more pronounced at short ranges.* If the target panel1 used in thi&test were fired upon in the same manner but at a range of approximately 50 yards, the horizontal distance between individual CB clusters would be reduced to approximately the distance between rounds within a cluster. At this range, the distribution of projectiles along the horizontal is comparable to the target area coverage provided by the extended burst of full automatic fire. The range at which target coverage is comparable will vary inversely as the average extreme spread (7ES of the controlled burst. Doubling the average extreme spread (Ei) of 4he controlled burst reduces to 25 yards the distances needed to obtain comparable target coverage. Two or mure riflemen engaging the same sweep-type target with the controlled-burst will more closely approach the target coverage provided by the full-automatic mode. Visual inspection of the target photographs (Appendix D) indicates that riflemen are not consistent from trial to trial (sweep to sweep) and do not place each burst in the same region of the panel. In addition, several rifleman tend to supplement each other. To illustrate, presented in Figures 5 and 6 are overplots of a single trial of L2 rounds for five riflemen engaging a sweep-type target with the controlled-burst and full-autmatic modes. The plots presented in Figures 7 through 11 provide a comparison of target region coverage and include all five trials of the 11 firers for the test condition listed. For a detailed description of a particular test condition refer to Appendix B. Note that the markings on the over- plots are abbreviations of the captions. 25 CONFI DENTIAL 4 '- S4Q -0 r0 0 40 60 (so aoo T' 5.5 I -1. ilts' 120 mi I Figure 6. Cotlled-busti, sweep target, standing, one trial of Firers 1 through 5 4Q* . , 26 140 160 CBT-CAL-S (141 Is) ?0U 0 -0 -40 ?0 -'C0 -40 V q) -0.4 ilns 40 3.4 mil1s Figure 7. Controlled-burst, calibration target, standing 27 .| :.I' . 44. "... i. *- U. US , ... co q 0I i 41 . "4-; LA. .. Li,.. L.. 40 44. • ... " ,L. • -L. S. : . . -. " V - .i.n. .0, , , :' :,: A"'. . "'i 0 .'; I= -. -' ". 00 .. 4-1 . .'1,, • . - .. , ,'.. * - . .. . CC ,.: -s ' ,., 14")" $.0 8t p C (a) 4) C .. ...... ,t CONFIDENTIAL 2. Controllbility. Targets ae not always visible and often it is necessary to direct rifle fire at an area where the enemy is known or suspected to be located. Large area targets are engaged by shifting accurate fire from one aim point to another or linearly across the target to cover the area systematically. For the purpose of this study, weapon controllability is defined as the ability of a rifleman to direct his rifle fire so that it strikes the target as close to the point (or line) of aim as possible. The panel was selected as a desirable target because the number of impacts recorded is maximized. The size, attitude, and range to a panel, taken with respect to the firer, are immaterial so long as the tactical target can be projected onto the panel. The wooded area presented in Figure 12 projects onto the target panel as a band approximately 10 inches high and extending the width of the panel. The range to the panel was selected so that 1 inch on the panel would represent an angular measurement of 2 mils. ~so, ,FRONT VEW - Figure 12 (U). Target area projected onto a target panel 29 CONFIDENTIAL COIDENTIAL The wooded area would be represented on an overplot by a band which is 10 mil above and below the centerline and approximately the width of the plot. Therefore, one method which measures relative controllability between modes of fire is to count impacts which strike within a designated band or zone of consideration across the center of a sweep-type target or about the center of a point-type target. Various sized bands drawn on the overplots of Figures 8 through 11 could be used to measure the relative target area coverage with the two modes of fire. The zone of consideration represented in Figure 13 has been subdivided into segments of equal width. Each segment has a height "a" and a width "b." 40 20 o,-I I ' -20 0 4O 60 -+I bl" 'L' 'i~ -20 -4,o Figure 13 (U). Dimensions 20 80 100 120 140 160 Zone of consideration, sweep target computer simulation and "b" were allowed to vary so as to represent a 5 x 1 1/2-foot man at ranges of 50 to 500 yards. The impact points for each trial (a total of 55 per test condition) of all 11 ",en were plotted and hits within the zone recorded. The number of segments hit and the number of hits within each segment were recorded for each range considered. Table XXI in Appendix C gives these data. 30 CONFIDENTIAL CONFIDENTIAL The curve prebented in Figuare 1)4 represents the ratio of the total nuber of segments hit with the full-automatic mode relative to the total number with the controlled-burst mode of fire. in,the full-automatic mode a continuous burst ofFor 12 each roundstrial was. when firedfiring at the " rate of approximately 450 shots per minute. When firing in the controlledburst made, four rapidly triggered bursts of three rounds each were fired. The rate. of-fire for the controlled burst is approximately 2000 shots per minute and the average extreme spread (RS)was 6.3 mils. L4 1.3 1.31) I.9 II i 1.1 01 ~YARDS FA 77 1.0 100 ' 200 300 400 500 0.9 XX 0.7 0.6 Figure 14 (U). Ratio of hit probability, FA to CB versus range The curve indicates that it is more advantageous tc engage a linear target at short range with extended burst, full-automatic fire. The fullautomatic mode of fire more uniformly distributes the projectiles along a linear target awid therefore increases the probability of a hit. At longer ranges the advantage shifts to the controlled-burst mode because the rifleman has more control over the placement of the burst and the projectiles are not in as tight a cluster. The range to crossover where Hewevez2 the advantage at Zonger ranges must be tempered somewhat by the reduced ZikeZihood of engaging targets at the Zonger' ranges. 31 CONFIDENTIAL i CONFIDENTIAL the advantage shifts from one mole of fire to the other is a function of the average extreme spread of the controlled burst, the average triggerpull rate of the rifleman and his rate of angular sweep when firing in the controlled-burst mode. The average trigger-pull rate during this test was 2.1 trigger pulls per second, or an ammunition expenditure (tactical rate of fire) of An increase in rate to 2.5 trigger approximately 380 rounds per minute. pulls per second would be necessary to equalize the rate of ammunition expenditure for the two modes of fire. As the trigger-pull rate is increased, the ability of the riflemuan to direct the fire of the controlled burst would be expected to decrease and the curve in Figure 14 would shift slightly upwara, The purpose of using the "number of segments hit" method for measuring controllability was that if the segment was stipulated to be the approximate size of a standing man, then counting the number of segments hit would provide a rough means of comparison. It was noted during the analysis that a large percentage of the segments received multiple hits, %especially with the controlled-burst mode. Table I presents a su-mmary of the percentage of segments receiving multiple hits for each mode and range. Table I (U). Percentage of Multiple Hits Versus Range Mode Range (yards) 100 4.2 200 FA 50 14.1 0B 60.9 42.4 18.3 1.9 300 4oo 500 - - - 8.5 8.4 5.5 At 200 yards, a larger percentage of the segments received multiple hits. This is understandable because at 200 yards a man 5 feet tall sub- tends an angle of approximately 8 1/2 mils and the average extreme spread for the controlled burst was 6.3 mils. We would expect the probability of a multiple hit to drop off rather repidly as the range approached 200 yards. 32 CONFIDENTIAL COIDEONTIAL The large percentage of multiple hits with the controlled-burst mode indicates that there were more impacts within the zone of consideration with this mode of fire. The curve plotted in Figure 15 represent. a ratio of the total number of rounds fired which impacted within the zone of I consideration. 100 -. F_. -A 1.0 200 300 l I 0.9 -(eS 500 400 , I I (35(6.3) 0,8 . X(78.9 ) 0.6 Figure 15 (U). Ratio of projectile impacts within the target area versus range, full-automatic to control led-burst modes This plot indicates that beyond approximately 200 yards, 15 to 20 percent more hits within a given target area can be expected with the controlled-burst mode of fire. At shorter ranges the uniformity of target area coverage must be considered. For those readers who prefer to perform statistical comparisons, there are presented in Tables IX through XIV of Appendix C various numerical measures of dispersion. We are unable to establish a single measure which includes all the elements of dispersion; hence, we have presented those which appear to be of interest. Figures 3 and 4 are examples of target patterns which are difficult to compare. Due to the additional components of dispersion that are introduced when a rapidly triggered controlled burst is employed against a sweep type target, a single best numerical measure for comparing patterns is difficult to select. ~33 CONFIDENTIAL I1 IL! i CONFIDENTIAL B. Pseudo-Tactical Test Besults This test provides a means of comparing the controlled burst to a two-to-five round trSger-manipulated (TM) burst of low rate full autOmatio fire when engaging, a linear array of visible point targets. A test condition employing a full automatic extended burst (30 rounds per burst) was tested- however, the results showed that this mode of fire is not appropriate for this array of targets. Table II presents a summary of the test results. A detailed description of the test as it was conducted is presented in Appendix B with the raw data presented in Appendix C. Table II (U). Line 1. Pseudo-Tactical Summary Sheet Description Trigger pulls/Second O, S* TM S* FA S* 1.3 1.2 NA** 3.0 3.3 30 (Rate of Target Engagement) 2. Rounds/Trigger Pull 3. Tactical Rate of Fire (Shots per Minute) 4. Targets Hit/Target Engaged (Successful Trigger Pull) *S 230 0.59 236 0.44 450 0.150 " - Standing Position - Do