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k TECHNICAL AIR INTELLIGENCE CENTER #21 REPORT EXAMINATION OF JAPANESE "BROWNING" MACHINE GUN l?JTm»GENCE LIBRABY 1 0 '-"•'• - i U . t , Issued by the D. vision 0f Naval Intelligence By Combined, Personnel * of United States an d British Services for the Use of All.ed Forces TECHNICAL AIR INTELLIGENCE CENTER NAVAL AIR STATION ANACOSTIA D C OPNAV-V #T 2 2 1 TAIC REPORT NO. 2 1 November 194 4 EXAMINATION OF JAPANESE "BROWNING" MACHINE GUM CBRD REPORT NO. 417 8 BY BATTELLE MEMORIAL INSTITUTE FOR WAR METALLURGY COMMITTEE DIV . 1 8 , NATIONAL DEFENSE RESEARCH COMMITTEE ISSUED BY THE DIVISION OF NAVAL INTELLIGENCE BY COMBINED IERSONNEL OF UNITED STATES AND BRITISH SERVICES FOR THE USE OF ALLIED FORCES TECHNICAL AIR INTELLIGENCE CENTER NAVAL AIR STATION ANACOSTIA, D.C . DISTRIBUTION! SEE PAGE 1 3 EXAMINATION OF JAPANESE "BROWNING" MACHINE GUN FOREWORD A Japanese aircraf t "Browning" .5 0 calibe r machine gun (BMI #437 - CEE #2950) S e r i a l #2349 , manufactured i n November 1942 , was receive d from th e Technica l Air Intelligenc e Center , Naval Air Station , Anacostia , D. C. for metallurgica l examination. The gun was captured at Iae , New Guinea, on September 16 , 1943, complete and i n good working order. I t had been used for a nominal period of time on a Japanese fighter CSCAR. Markings found on the gun are recorded i n Figure 3 of the Appendix. The weapon weighed 51-1/2 pounds when received . Seventeen per cent of the metal parts used in the manufacture of the Japanese "Browning" .50 calibe r machine gun were made from tungsten steel , three per cent from nickel-chromium steel , and the remainder were unalloyed. The steel s were made in the basic open hearth or electri c furnace with graded scrap forming a large part of the charge. The weapon was copied from an early American model with minor modifications . Heat treat - Bents were simpler than American practices , and flame hardening was used extensively . An inter estin g feature was chromium plating i n the bore of the barrel . ECONOMIC COIBIDERATIONS The gun shows manufacturing methods similar t o other Japanese guns examined and displayed good workmanship. Bearing parts possessed a good finis h while a large number of exterior sur faces showed hand finishing . No brazed or stamped parts were used. Contrary t o American and German practices , but in keeping with their own, the Japanese used high-carbon tungsten stee l (carbon .59% - .67%, tungsten 1.7% - 2.2%) in parts subjected t o extreme wear. Residual amounts of other alloying elements indicate the use of graded scrap in th e furnace charges. The extensive use of flame hardening on the parts i s an indication of conservation of heat - treatin g equipment. DISCUSSION OF RESUITS The Japanese "Browning" machine gun as-received and disassembled i s shown i n Figures 1 t o 3 , inclusive , in the Appendix. While thi s gun was obviously copied from an early American design, some features are of interes t and are discussed in detail . The bore of the barre l of thi s gun was chromium plated from the shoulder of the chamber t o the muzzle. Very l i t t l e wear had occurred a t each end where the plating showed a thickness of .000080 inch . The plating was almost entirel y removed from the shoulder up to about 6 inches back of the muzzle. The chromium plating seemed t o have a satisfactor y adherence, as there was no evidence of flaking off . This barrel had apparently had considerable service . Type of Stee l Each part was spark teste d and carefull y inspected. Those showing unusual features we^e analyzed and the result s shown i n Tables 1 and 2 i n the Appendix. Twenty parts were found t o contain tungsten in libera l amounts. The use of tungsten steel s i n machine guns appears t o be standard Japanese practice as evidenced in previous reports sub mitted on thi s project . The choice of thi s allo y appears t o be on the basi s that these parts are subjected to extreme wear. However, as evidenced by the physical test s made on the gun barrel (Table 3 ) , i t i s doubtful that the wear resistance of tungsten steel s would be improved over tha t of a plai n carbon stee l of equal hardness. The carbon and tungsten level s used are not high enough to/produce wear-resistant , free tungsten carbide particles , and the parts are not massive enough t o require any alloyin g element for hardenability . - 1 The steels appear to have been made In the basic open hearth or electric furnace. They were •ilicon and aluminum killed. The residual amounts of various alloying elements indicate the use of considerable scrap in the charges. Aluminum may have been added in some cases for grain size control. A minor number of small parts were made from high-sulphur screw stock for its free machin ing qualities. Heat Treatment Seventy-two per cent of the 115 parts examined were heat treated. This is a high percent age for Japanese practice, but the treatments appear simpler than American specifications since only the firing pin and the extractor were differentially hardened. The bolt, for example, was uniformly heat treated to a lower hardnese than specified on the American counterpart. Hardening of wearing parts was accomplished by flame heating and quenching. Method of Manufacture Of a total of 115 parts available for examination, the following distribution according to manufacturing method was made: 22% - Forged and machined 1+2$ - Machined from bar stock 11$ - Coiled wire springs U& - Cut from rod or wire 11$ - Cut from plate or sheet These ratios are in proportion to other Japanese machine guns examined. However, the advan tage of forging was largely lost through improper forging and machining. Careful examination of the barrel revealed that it had been rifled rather than broached* Exterior Coatings All the outer parts of the gun were given an oxide chemical treatment by dipping to produce a dark dull finish. This treatment, while producing some corrosion resistance, is designed prin cipally to reduce reflectivity. The automatic trigger housing (#97) was nickel plated .00006" on the entire exterior surface; the auxiliary hand-cocking lever extension (#112) was cadmium plated .0002"j and the breech lock depressors (#17) were chromium plated e00005 n over the flame hardened wearing surface. -2 27723 Figure 1. Japanese "Browning" 12.7 mm. (.50 cal.) machine gun as- received. (BMI #437) - Figure 2. Japanese "Browning" 12.7 mm. machine gun disassembledo (CEE #2950) -3 30821 27722 Figure 3. Close-up view of .housing assembly attachments -A 31309 Figure L. Macroetched view of the accelerator showing flow lines and flame-hardened area. IS w ^̂ Www ^ & ^ > • 'i Figaro 5. Micrograph of typical tungsten steel core, Nital Etch 1000X Vickers Hardness 280 i Li 1 -5 TABLE 1. DETAILS OF MANUFACTURE OF JAPANESE "BROWNING" .50 CALIBER MACHINE GUN (BMI #437 - CEE #2950) Part Weight, Hardness, Microstructure and No. Name Grams Vickers Remarks Heat Treatment 1 Housing Assembly 8,825 248 Three forgings and two Quenched and highly plates of SAE 1080 steel tempered. riveted together. Rivets of low carbon steel. 2 Housing Cover 736 268 Forged from SAE 1080 steel. Quenched and tempered. Not differentially hardened. 3 Housing Cover -atch 27 312 Forged from medium carbon Quenched slightly below steel. the critical range and tempered. 4 Housing Cover Latch 53 258 Two pieces machined from Quenched and•tempered. Guide bar stock and fusion Heat treated after welded together. welding. 5 Housing Cover Latch 7 Stamped from high carbon Spring steel sheet. 6 Housing Cover Latch 4 536 Cut from medium carbon Quenched and tempered, Pin steel rod. 7 Housing Cover Guide 127 core 255 Forged from medium carbon Quenched and tempered. case 613 steel. Flame hardened Flame heated and case .05" on wearing quenched. surface. 8 Barrel 2,975 295 Forged from tungsten sbeeL Quenched and tempered. Rifled bore. 9 Barrel Extension 1,320 core 258 Forged from tungsten steeL Quenched and tempered. case 689 Flame hardened in groove Shows small MnS in- corners only. clusions. Flame hardened. 10 Barrel Jacket 909 220 Machined from SAE 1040 Annealed. Excess MnS steel bar stock or inclusions. tubing. 11 Barrel Jacket 291 351 Machined from medium car- Quenched and tempered. Extension bon steel bar stock or tubing. 12 Barrel Booster 95 273 Machined from tungsten Quenched and tempered. steel bar stock. 13 Barrel Booster H4 267 Machined from medium car- Quenched and tempered. Retainer bon steel bar stock. 13A Barrel Booster 8 580 Machined from medium car* Quenched and slightly Retainer Lock bon steel sheet. tempered. U Breech Lock 151 core 480 Machined from tungsten Quenched and tempered case 733 steel bar stock. Flame core. Flame heated hardened on top wearing .O65w and quenched. surface. 15 Breech Lock Cam 284 292 Forged from low tungsten Quenched and tempered. steel* 16 Breech Lock Cam Bolt 38 187 Machined from mild carbon Normalized. steel bar stock. 17 Breech Lock 22 core 505 Machined from medium car- Core quenched slightly Depressors case 795 bon steel bar stock. below critical range Flame hardened on wear- and tempered. Shows ing surface and chrome undlssolved carbides. plated .00005w. Case flame heated .08" and quenched. 18 Breech Lock 1 Machined from low carbon Normalized. Shows MnS 195 Depressor Pin steel bar stock. inclusions. 18A Breech Lock Pin 15 483 Machined from tungsten Quenched and tempered. steel bar stock. 18B Breech Lock Spring High carbon steel strip. -6 TABLE 1. (CQWT.1) Part Weight, Hardness, Microstructure and No. Name Grams Vickers Remarks Heat Treatment 19 Belt Feed Cover 84 345 Forged from medium car bon steel bar stock. Quenched below critical range and tempered. Shows undissolved car 20 Belt Feed Pawl 360 Machined from medium car bides . Quenched below critical 35 bon steel bar stock. range and tempered. Shows undissolved car bides. 21 Belt Feed Pawl 458 Forged from medium carbon steel. Riveted to pawl. Quenched and tempered. Shows undissolved carbides. 22 Belt Feed Pawl Pins 3 218 Cut from medium carbon Hot rolled and normaliz steel rod. ed. 23 24 Belt Feed Pawl Spring Belt Feed Lever 1 152 337 High carbon steel coiled wire spring. Forged from medium carbon Cold drawn. Quenched below critical steel bar stock. Flame hardened on tips. Not range and tempered. Shows MnS inclusions differentially hardened. and undissolved car bides. Flame heated .36" and quenched. 25 Belt Feed Lever Bolt 27 295 Machined from medium car- Normalized. bon steel bar stock. 26 Belt Feed Lever Washer 2 200 Cut from low carbon steel Rolled and normalized. sheet. 27 Cartridge Feed Retainer 22 core 383 case 713 Machined from medium car bon steel bar stock. Flame hardened on wear- Core quenched and tem pered. Case flame heated .08" and tem 23 29 30 Cartridge Feed Hinge Pin Cartridge Feed Retainer Spring Cartridge Receiver Stop 7 62 174 270 ing surface. Machined from medium car bon steel bar stock. High carbon steel coiled wire spring. Machined from medium car bon steel bar stock. pered. Spheroidized condition. Cold drawn. Quenched and highly tem pered. Shows undis solved carbides. 31 Cartridge Receiver Pin 3 Low carbon steel. Hot rolled and normal ized steel. Hot head ed and annealed. 32 Bolt 1,556 303 Machined from tungsten steel bar stock. Quenched and tempered. 33 Bolt Decelerator 64 core ease 265 713 Machined from tungsten steel bar stock. Flame Quenched and tempered. Case heated by flame hardened on wearing and quenched. surface. 34 Bolt Decelerator Hinge 19 pin arm 258 168 Pin machined from medium carbon steel bar stock. Arm cut from high carbon Pin rolled and normal ized. Arm spheroi dized. steel strip. Pin mach ined down at head and used as rivet to attach arm. 35 36 37 Bolt Decelerator Spring Bolt Decelerator Spring Cap Bolt Decelerator 1 5 37 319 415 High carbon steel coiled wire spring. Machined from medium car bon steel bar stock. Cut from drawn wire. Cold drawn. Quenched and tempered. Cold drawn. Spring Cap Locking 38 Pin Bolt Release Lever 40 405 Forged from medium car bon steel. Quenched and tempered. -7 TABIE 1. (CONT.) Part Weight, Hardness, Microstructure and Name Grams Vickers Remarks Heat Treatment No. 39 Bolt Release Lever 16 490 Machined from tungsten Quenched and tempered. Pin steel bar stock. 40 Accelerator 168 core case 360 628 Forged from tungsten steel. Flame hardened on wearing surface (see Figure 4). Core quenched slightly below critical range and tempered. Case flame heated .08" and quenched. Accelerator Pin 27 423 Cut from medium carbon steel rod. Quenched and tempered. Shows small amounts of undissolved car bides . 42 Accelerator Catch 93 core case 280 700 Forged from tungsten steel. Flame hardened on working surface. Quenched and highly tempered. Shows tita- nium nitride and MnS inclusions. Flame hardened .25" and quenched. 43 Accelerator Catoh Lock Pin 3 245 Cut from mild carbon steel rod. Rolled and rapidly cooled. 44 Accelerator Lock 19 510 Cut from high carbon Quenched and tempered. 45 46 Spring Firing Pin Firing Pin Spring 13 11 back point 575 883 steel sheet. Forged from tungsten steel bar stock. High carbon steel coiled Differentially quenched and uniformly tempered. Cold drawn. 47 Firing Pin Spring Container 55 388 wire spring. Machined from tungsten steel bar stock. Quenched and tempered. Shows MnS inclusions. 48 Firing Pin Spring • Stop Pin 379 Cut from medium carbon steel rod. End ma- Quenched and tempered. Shows excess carbides. 8 chined down and used as rivet to attach arm. 49 Firing Pin Spring • Stop Arm 419 Cut from medium carbon steel sheet. Quenched and tempered. Shows excess carbides and titanium nitride inclusions. 50 Sear 18 395 Forged from Ni-Cr-fl steel Quenched and tempered. but not differentially hardened. 51 Sear Spring 1 - High carbon steel coiled Cold drawn. 52 Sear Slide 5 395 wire spring. Machined from low Ni-Cr steel bar stock. Quenched and tempered. 53 54 Cocking Lever Driving Spring Rod 17 99 404 186 Forged from tungsten steel. Machined from mild carbon Quenched and tempered. Hot rolled and normal- steel. Head and rod one ized. 55 Outer Driving Spring 81 608 piece. High carbon steel coiled Cold drawn. 56 Inner Driving Spring 33 - wire spring. High carbon steel coiled Cold drawn. 57 Extractor 82 core case 280- 379 ,432 wire spring. Forged from tungsten steel* Flame hardened and dif ferentially heat treated, Differentially quenched and uniformly tempered. Flame heated .055" and 58 59 Extractor Depressor Extractor Cam Guide 16 35 core case 608 312 509 Stamped from high carbon steel sheet. Forged from medium carbon steel . quenched. Quenched and slightly tempered. Quenched and tempered. Flame hardened .04° on edges and quenched. -8 TABIE 1. (CONT.) Part Weight, Hardness, Micro8tructure and Ho. Name Grains Vickers Remarks Heat Treatment 60 Extractor Cam Guide 5 153 Machined from loir carbon Normalized. Nut steel bar stock. 61 Extractor Cam Guide 1 570 High carbon steel wire Cold drawn. Spring clip. 62 Ejector 9 293 Forged from medium carbon Quenched and tempered. steel bar stock. 63 Ejector Spring - - High carbon steel coiled Cold drawn. 64 Ejector Pin 1 261 wire spring. Cut from medium carbon Quenched and highly 65 Recoil Housing 795 284 steel rod. Forged from tungsten tempered• Quenched slightly below steel. •Oil". Carburized case the critical range and tempered. Case is quenched and tempered showing undis8olved carbidos. 66 Main Recoil Spring 127 362 SAE 1070 Modified steel coiled wire spring. Cold drawn. Decarbur ised surface. 67 Secondary Recoil . Spring 46 326 SAE 1080 steel coiled wire spring. Cold drawn. 68 Spring Buffer Tube U6 266 Machined from medium car bon steel bar stock. Quenched and highly tempered. Shows un dissolved carbides. 69 Spring Buffer Tube Rod 45 435 Machined from medium car bon steel bar stock. Quenched and tempered. Shows MnS inclusions and undi3solved car bides • 70 Spring Buffer Tube Guide 33 220 Hot headed from medium carbon steel. Annealed after heading operation. 71 Spring Buffer Tube Cap 16 179 Machined from mild car bon steel screw stock. Normalised. 72 Spring Buffer Tube Head 29 302 Machined from low tungs ten steel bar stock. Quenched and tempered. Shows excess carbides. 73 74 75 Spring Buffer Tube Inner Spring Spring Buffer Tube Outer Spring Spring Buffer Tube Seat 8 29 62 - 562 400 High carbon steel coiled wire spring. High carbon steel coiled wire spring. Machined from tungsten steel bar stock. Cold drawn. Cold drawn and tempered, Decarburized .004"• Quenched and tempered. Shows large amounts of MnS inclusions. 76 Spring Buffer Tube Cover 72 core 300 case 700 Machined from SAE 1070 modified steel bar stock. Face,flame Quenched and tempered. Base flame heated and quenched. hardened. 77 Spring Buffer Tube Pin 4 284 Cut from medium carbon steel rod. Quenched and tempered. Shows signs of decar bur izat ion. 78 79 Auxiliary Buffer Spring Back Plate 65 850 500 300 SAE 1080 steel coiled wire spring. Forged from SAE 1080 carbon steel. Quenched and tempered. Decarburlzed .003"• Quenched and highly tempered. Shows excess carbides• 80 Back Plate Cap 99 144 Machined from medium car bon steel bar stock. Highly annealed. 81 Back Plate Bolt 111 240 150 Ditto Machined from mild carbon Annealed, Normalised, 82 Back Plate Bolt Nut 5 steel bar stock. 83 Back Plate Latch Pin 17 374 Machined from medium car bon steel bar stock. Quenched and tempered. -9 TABLE 1. (CONT.) Part We ight, Hardnes s, Microstructure and No. Name Grams Vickers Remarks Heat Treatment 84 Back Plate Lock Bolt 61 260 Machined from AESI Normalized. A513O steel bar stock. 85 Pin Cocking Lever 11 440 Forged from medium car- Quenched and tempered. bon steel. 86 Trigger Bar Extension 64 core case 385 689 Machined from tungsten steel. Quenched and tempered. Carburized case .04" on ends. 87 Trigger Bar Extension Pin 17 pin arm 400 175 Pin cut from medium car bon steel bar stock. Arm cut from high car- Pin quenched and temp ered. Arm spheroi dized. bon steel strip. Pin machined down at head and used as rivet to attach arm. 88 Mechanical Trigger 23 660 Forged from medium car bon steel* Quenched and sligb ly tempered. 89 Mechanical Trigger High carbon steel coiled 90 Spring Mechanical Trigger Guide 33 weld metal 134 190 wire spring. Welded bar stock and curved metal of medium Not heat treated after welding. Normalized. carbon steel. 91 Mechanical Trigger Screws 1 292 Machined from mild car bon steel. Quenched and highly tempered. 92 93 94 Mechanical Trigger Nut Automatic Trigger Automatic Trigger Retainer 3 6 10 core case core case - 365 700 376 680 Cut from mild carbon steel. Machined from Ni-Cr steel bar stock. Machined from Ni-Cr steel bar stock. Quenched and tempered. Carburized .04" deep on tip . Quenched and tempered. Carburized on wearing 95 Automatic Trigger •30 core 374 Ditto surface .04" deep. Ditto Piston case 708 96 Automatic Trigger 0ft 536 High carbon steel coiled wire spring. Cold drawn wire. Spring Machined from low carbon Annealed. 97 Automatic Trigger 255 124 Housing steel bar stock. Nickel 98 99 100 101 102 103 104 105 106 Automatic Trigger Butterfly Nut Automatic Trigger Pressure By-pass Automatic Trigger Housing Bolts Automatic Trigger Housing Attachment Bolts Automatic Trigger Housing Attachment Nuts Automatic Trigger Housing Attachment Washers Hand Cocking Lever Hand Cocking Lever Stud Hand Cocking Lever Pin 25 25 3 16 11 4 410 18 11 160 steel 164 copper 133 205 - 218 216 200 350 410 plated on exterior .00006". Machined from medium car bon steel bar stock. Machined from medium car bon steel bar stock and copper bushed. Headed from mild carbon steel. Headed from mild carbon steel. Cut from mild carbon steel bar stock. Cut- from mild carbon steel bar stock. Hook bent from medium carbon steel. Machined from medium carbon steel bar stock. Cut from medium carbon steel rod. Rolled and annealed. Steel normalized. Copper cast. Hot headed and annealed. Hot headed and annealed* Normalized. Normalized. Normalized. Quenched below critica l range and tempered. Quenched below critica l range and tempered. -10 TABLE 1. Part Weight, Hardness, Microstructure and No. Name Grams Vickers Remarks Heat Treatment 107 Hand Cocking Lever 29 200 Machined from mild car- Normalized. Front Guide Bracket bon steel plate. 108 Hand Cocking Lever 13 316 Machined from mild car- Quenched and tempered. Front Guide Bracket bon steel plate. Seat 109 Hand Cocking Lever 37 182 Machined from mild car- Normalized. Rear Guide Bracket bon steel plate. 110 Hand Cocking Lever 3 226 Headed from screw stock. Hot headed and annealed. Cap Screws 111 Auxiliary Hand Cocking 709 100 Cut from rolled plate. Annealed. Lever Low carbon steel . 112 Auxiliary Hand Cocking 70 136 Ditto Annealed. Lever Extension Cadmium plated .0002". 113 Auxiliary Hand Cocking 40 203 Machined from screw Normalized. Lever Coupling stock. 1 U Auxiliary Hand Cocking 7 220 Machined from screw Normali^d. Lever Bolt stock. 115 Auxiliary Hand Cocking 4 250 Machined from screw Normalized. Lever Bolt stock. TABLE 2 . ANALYSES OF SELECTED PARTS OF JAPANESE "BROWNING" MACHINE GUN (BMI #437 - CEE #2950) Part Chemical S pe ctr oerarihic No. Name C P s Mn S i Ni Cr W Mo Cu Sn Al V** Ti** 1 Housing .80 .020 .023 .55 .33 .15 .07 <;oi .016 .29 .11 .009 8 9 Assembly Barrel Barrel Extension .60 .61 .012 .ou .028 .ou .42 .43 .32 .20 .17 .20 .16 . U 2.23 1.89 .011 .019 .24 .31 .ou .065 .030 .053 12 Barrel Booster .64 .023 .023 .53 .47 .20 .12 2.08 .020 .28 .071 .012 U Breech Lock .59 .026 .019 .48 .27 .17 .17 2.20 .017 .23 .057 .008 15 Breech Lock Cam .71 .020 .022 .45 .28 .17 .21 .58 .017 .23 .090 .013 18A Breech Lock Pin .64 • .025 .63 .53 .16 .12 1.85 .011 .23 .041 .008 32 Bolt .62 .024 .021 .47 .27 .24 .17 1.70 .022 .26 .067 .018 33 Bolt .70 .034 .019 .44 .30 .20 .20 1.20 .016 .23 .042 .010 Decelerator 39 Bolt Release .76 .026 • .41 .30 .13 .07 2.10 .006 .20 .043 .011 40 Lever Pin Accelerator Accelerator .66 .68 .020 .034 .021 .021 .47 .44 .21 .29 .20 .21 .19 .11 2.05 1.85 .26 .008 .26 .27 .050 .054 .018 .028 .026 45 Ul Catch Firing Pin Firing Pin # .75 -* .025 * .016 .58 .42 .30. .37 .12 . U . U .19 2.05 2.08 .013 .021 .25 .26 .036 .066 .015 .0U .033 Spring Con # 50 53 57 tainer Sear Cocking Lever Extractor .37 .67 .70 .023 .025 .025 * .011 .015 .57 .37 .54 .37 .22 .32 3.70 .15 .21 1.54 .18 .08 .08 1.70 1.88 .11 .025 .012 .33 .22 .23 .12 .053 .045 .019 .ou .015 65 66 Recoil Housing Main Recoil .61 .73 .031 .020 .025 • .46 .28 .24 .23 .15 .05 . U .09 1.84 <£.01 .017 .006 . .24 -£.04 .056 .004 .015 <.005 67 Spring .Secondary .81 .030 .037 .62 .34 .06 -£.03 <.01 .005 .U .092 .019 Recoil Spring -11 TABLE 2 (CONT.) Part lemlca! I SpectrocraDhic No. Name C P S Mn S i Ni Cr W Mo Cu Sn Al V** Ti*» 72 Spring Buffer .88 .038 • .52 .29 .28 .23 .18 .009 .24 .068 .017 Tube Head 75 Spring Buffer .67 .025 .026 .42 .25 .16 .13 1.75 .016 .24 .080 .014 Tube Seat 76 Spring Buffer .75 .038 .026 .70 .33 .13 .38 -<.01 .030 .29 .14 .014 Rube Cover 78 Auxiliary .77 .044 .056 .76 .37 .05 -c.03 <:.01 -<.005 .20 ~ .14 .006 Buffer Spring 84 Back Plate .32 .025 .024 •44 .26 .11 1.03 <.01 .22 .023 .018 .u Lock Bolt 86 Trigger Bar * * * .52 .32 .18 .17 2.22 -C005 .16 .037 .014 Extension 93 Automatic * * * .48 .25 3.29 1.09 <.01 <.005 .33 .058 .010 Trigger 94 Automatic * * # .30- .25- 3.00 - .90- <^.01 .10- .45- .05- <.005 Trigger .40 .35 3.50 1.10 .20 .55 .15 Retainer 95 Automatic * * .48 .26 3.30 1.02 <.01 <.005 .21 .098 <C.005 Trigger Piston * Insufficient sample for analysis. ** Vanadium ( .004) except where shown. Titanium ( .004). TABIE 3. PHYSICAL TEST DATA* (BMI #437 - CEE #2950) Per Cent Per Cent lie Id Tensile Impact Part Type Reduction Elongation, Strength, Strength, Charpy V- Hard- No. Name Steel ef Area In 2" p.s.l . p.s.i . Notch, ness Ft . Lbs. 1 A Housing SAE 1080 29.2 14.6 91,500 136,000 Rc*21 Plates B 40 17.8 89,000 133,000 8 A Barrel 50.3 23 102,500 134,000 31 Re'29 B 2-1/456 49.8 23 112,000 134,000 33 Tungsten * Standard .505" x 2" A.S.T.M. specimens. -12 py T.TRT NAVY Copies The Commanding Officer, Naval Air Station, Anacostia 20, D. C. 1 The Commanding Officer, Naval Air Station, Patuxent River, Maryland 2 BuAer, Equipment & Material Section, Room 2*36, Navy Dept. 1 BuAer, Aircraft Maintenance, Navy Department, Room 1N69 1 BuAer, Technical Information, Navy Department, Room W5U 1 BuAer, Military Requirements, Navy Department, Room 2916 1 BuAer, Armament, Navy Department, Washington, D. C. 1 DCNO (Air) , Navy Department, Room 2082 1 Op-l6-Z, Munitions Bldg. , Room 1226, Attn: Comdr. J . L. Rlheldaffer 2 Executive Office of Secretary, Naval Research and Development, Navy Dept., Rm. 0U8 1 Naval Liaison Officer, Army Air Forces Board, Orlando, Florida 1 Naval Liaison Officer, Proof Division, Army Proving Ground Command, Eglin Field, Fla. 1 BuQrd, RE-7, Navy Department, Washington, D. C. 1 ARMY Military Intelligence Service , Distribution Branch, War Department, Pentagon Bldg., Room 2C-800, Washington, D. C. U Headquarters Army Air Forces, Development Engineering Branch, M & S, Washington, D.C. 1 Army Air Forces, Materiel Command, Wright Field , Dayton, Ohio, Attn: Chief Evaluation Branch, Technical Data Laboratory 2 Research and Developments Division, Army Service Forces, Room 4E-632, Pentagon Bldg. , Washington, D. Co U President, Army Air Forces Board, Orlando, Florida 3 Commanding General, School of Applied Tactics , Orlando, Florida 3 Air Ministry, AI2(g) , Whitehall, London S.W. 1 8 Air Member, New Zealand Joint Staff Mission, Munitions Bldg. , Room 2501 2 Canadian Joint Staff , 2222 S Street , Washington, D. C. Air Member - Attnt Air Intelligence Office U Naval Member - Attn: Naval Intelligence Office 1 British Air Commission, 1785 Mass. Ave., Washington, D. C. 2 Royal Australian Air Force Representative, Munitions Bldg. , Room 4503, Washington, D. C. 3 Naval Air Representative, Room 3H11, Navy Department, Washington, D. C. 2 National Bureau of Standards, Conn. Ave. at Upton St. , Washington, D. C. Attn: Mr. W# F. Roeser The National Advisory Committee for Aeronautics, 1500 New Hampshire Ave., Washington, D. C. TAI UNITS Headquarters, Far East Air Force, A.P.O. 925, c/o Postmaster, San Francisco, Calif. , Attn: Technical Air Intelligence Unit m t , , . . T «. , , , „<+ o ConAirPac, F.P.O., San Francisco, Calif. , Attn: Technical Air Intelligence Unit 2 Hq., 14th Air Farce, A.P.O. 627, c/o Postmaster, New York City, Attn: Technical Air Intelligence Unit . * Allied TAI Unit, c/o Naval Liaison Office, A.P.O. 465, New York City, N. Y. 2 -13
