HEADQUARTERS FM 3-22.68 DEPARTMENT OF THE ARMY CREW-SERVED MACHINE GUNS, 5.56-mm AND 7.62-mm M249, 5.56-MM MACHINE GUN M60, 7.62-MM MACHINE GUN M240B, 7.62-MM MACHINE GUN JANUARY 2003 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. *FM 3-22.68 FIELD MANUAL HEADQUARTERS No. 3-22.68 DEPARTMENT OF THE ARMY Washington, DC, 31 January 2003 CREW-SERVED MACHINE GUNS, 5.56-mm AND 7.62-mm CONTENTS Page PREFACE......................................................................................................................... vi CHAPTER 1. M249 MACHINE GUN Section I. Description and Components................................................................ 1-1 1-1. Description................................................................................ 1-1 1-2. Components.............................................................................. 1-3 1-3. Ammunition.............................................................................. 1-5 1-4. Blank Firing Attachment .......................................................... 1-8 Section II. Maintenance.......................................................................................... 1-9 1-5. Clearing Procedures.................................................................. 1-9 1-6. General Disassembly.............................................................. 1-11 1-7. Inspection................................................................................ 1-16 1-8. Cleaning, Lubrication, and Preventive Maintenance.............. 1-18 1-9. General Assembly................................................................... 1-21 1-10. Function Check....................................................................... 1-24 1-11. Maintenance Procedures......................................................... 1-25 1-12. Maintenance During Nuclear, Biological, Chemical Conditions............................................................................... 1-25 Section III. Operation and Function ...................................................................... 1-25 1-13. Operation ................................................................................ 1-25 1-14. Loading................................................................................... 1-26 1-15. Unloading ............................................................................... 1-27 1-16. Cycle of Functioning .............................................................. 1-27 1-17. Sights ...................................................................................... 1-29 1-18. M122 Tripod........................................................................... 1-31 1-19. Dismounting from the M122 Tripod ...................................... 1-33 1-20. Bipod Operations.................................................................... 1-33 1-21. Vehicular Mount..................................................................... 1-34 1-22. Tripod Positioning.................................................................. 1-34 DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. *This publication supersedes FM 23-67, 29 February 1984 and FM 23-14, 26 January 1994. i FM 3-22.68 Page Section IV. Performance Problems and Destruction ............................................. 1-34 1-23. Malfunctions........................................................................... 1-34 1-24. Stoppages................................................................................ 1-35 1-25. Immediate Action ................................................................... 1-37 1-26. Remedial Action..................................................................... 1-38 1-27. Destruction Procedures........................................................... 1-38 CHAPTER 2. M60 MACHINE GUN Section I. Description and Components................................................................ 2-1 2-1. Description................................................................................ 2-1 2-2. Components.............................................................................. 2-3 2-3. Ammunition.............................................................................. 2-6 2-4. Blank Firing Attachments, M13 and M13A............................. 2-7 Section II. Maintenance.......................................................................................... 2-9 2-5. Clearing Procedures.................................................................. 2-9 2-6. General Disassembly.............................................................. 2-10 2-7. Inspection................................................................................ 2-16 2-8. Cleaning, Lubrication, and Preventive Maintenance.............. 2-17 2-9. General Assembly................................................................... 2-19 2-10. Function Check....................................................................... 2-21 2-11. Maintenance Procedures......................................................... 2-22 2-12. Maintenance During Nuclear, Biological, Chemical Conditions............................................................................... 2-22 Section III. Operation and Function .......................................................... 2-22 2-13. Operation ................................................................................ 2-22 2-14. Loading................................................................................... 2-22 2-15. Unloading…. .......................................................................... 2-23 2-16. Cycle of Functioning .............................................................. 2-23 2-17. Sights ...................................................................................... 2-25 2-18. M122 Tripod........................................................................... 2-26 2-19. Bipod Operations.................................................................... 2-28 2-20. Vehicular Mount..................................................................... 2-29 2-21. Tripod Position ....................................................................... 2-30 Section IV. Performance Problems and Destruction ............................................. 2-30 2-22. Malfunctions........................................................................... 2-30 2-23. Stoppages................................................................................ 2-31 2-24. Immediate Action ................................................................... 2-32 2-25. Remedial Action..................................................................... 2-33 2-26. Destruction Procedures........................................................... 2-34 CHAPTER 3. M240B MACHINE GUN Section I. Description and Components................................................................ 3-1 3-1. Description................................................................................ 3-1 3-2. Components.............................................................................. 3-3 3-3. Ammunition.............................................................................. 3-5 3-4. Ammunition Adapter................................................................ 3-6 ii FM 3-22.68 Page 3-5. Blank Firing Attachment .......................................................... 3-7 Section II. Maintenance.......................................................................................... 3-9 3-6. Clearing Procedures.................................................................. 3-9 3-7. General Disassembly.............................................................. 3-11 3-8. Inspection................................................................................ 3-18 3-9. Cleaning, Lubrication, and Preventive Maintenance.............. 3-20 3-10. General Assembly................................................................... 3-24 3-11. Function Check....................................................................... 3-27 3-12. Maintenance Procedures......................................................... 3-27 3-13. Maintenance During Nuclear, Biological, Chemical Conditions............................................................................... 3-27 Section III. Operation and Function ...................................................................... 3-27 3-14. Operation ................................................................................ 3-28 3-15. Loading................................................................................... 3-28 3-16. Unloading ............................................................................... 3-28 3-17. Cycle of Functioning ............................................................. 3-29 3-18. Sights ...................................................................................... 3-30 3-19. M122A1 Tripod...................................................................... 3-33 3-20. Bipod Operations.................................................................... 3-35 3-21. Tripod Operations................................................................... 3-36 Section IV. Performance Problems and Destruction ............................................. 3-36 3-22. Malfunctions........................................................................... 3-36 3-23. Stoppages................................................................................ 3-37