TROUBLESHOOTING PROCEDURES FOR
CORRECTIVE ACTION
1. FAILURE OF MAGAZINE TO LOCK IN RIFLE/CARBINE.
Step 1. Inspect for dirty or corroded magazine catch (1).
Disassemble and clean (WP 0021).
1. FAILURE OF MAGAZINE TO LOCK IN RIFLE/CARBINE - Continued.
Step 2. Inspect for defective magazine catch spring (2).
Replace magazine catch spring (WP 0021).
Step 3. Inspect for worn or broken magazine catch (1).
Replace magazine catch (WP 0021).
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1 2
Figure 1. Magazine Catch Inspection.
2. FAILURE TO FEED.
Step 1. Inspect for weak or broken magazine catch spring (2).
Replace magazine catch spring (WP 0021).
Step 2. Inspect for defective magazine catch (1).
Replace magazine catch (WP 0021).
Step 3. Determine if magazine catch (1) is out of adjustment (will not retain magazine).
Refer to TM 9-1005-319-10.
Step 4. Check for short recoil.
See Malfunction 10.
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1 2
Figure 2. Magazine Catch and Spring Inspection.
3. FAILURE TO CHAMBER.
Step 1. Inspect for weak or broken action spring (3). RIFLE ONLY: Free length should be 11 3/4 in. (29.85 cm) minimum to 13 1/2 in. (34.29 cm) maximum. CARBINE ONLY: Free length should be 10 1/16 in. (25.56 cm) minimum to 11 1/4 in. (28.58 cm) maximum.
Replace action spring (WP 0021).
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3
Figure 3. Action Spring.
Step 2. Check for short recoil.
See Malfunction 10.
4. FAILURE TO LOCK.
Step 1. Inspect for missing bolt cam pin (4).
Replace bolt cam pin (WP 0011).
Step 2. Inspect for damaged bolt carrier key (5).
Repair slightly dented bolt carrier key. Replace more seriously damaged bolt carrier key (WP 0013).
Step 3. Inspect for loose screws (6) on bolt carrier key (5).
a. Disassemble and repair (WP 0013).
b. Reassemble using new screws.
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4 5
6
Figure 4. Bolt Carrier Assembly Inspection.
Step 4. Inspect for improperly assembled extractor spring assembly (7).
Assemble correctly (WP 0012).
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7
Figure 5. Extractor Spring Assembly Inspection.
Step 5. Inspect for bent gas tube (8).
a. Adjust to original configuration by bending gas tube in area of handguards.
b. Replace gas tube and check alignment (WP 0015).
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8
Figure 6. Gas Tube.
Step 6. Inspect for weak or broken action spring (3). RIFLE ONLY: Free length should be 11 3/4 in. (29.85 cm) minimum to 13 1/2 in. (34.29 cm) maximum. CARBINE ONLY: Free length should be 10 1/16 in. (25.56 cm) minimum to 11 1/4 in. (28.58 cm) maximum.
Replace action spring (WP 0021).
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3
Figure 7. Action Spring Inspection.
Step 7. Check for short recoil.
See Malfunction 10.
5. FAILURE TO FIRE.
Step 1. Inspect for carbon buildup in firing pin recess inside bolt assembly.
Remove cartridge extractor and clean recess with pipe cleaner (WP 0045, item 11); see TM 9-1005-319-10.
5. FAILURE TO FIRE - Continued.
Step 2. Inspect for broken hammer (10).
Replace hammer (WP 0021 and WP 0023).
Step 3. Inspect for broken hammer spring (9).
Replace hammer spring (WP 0021 and WP 0023).
Step 4. Check for improper assembly of hammer spring (9).
Assemble properly (WP 0023).
Step 5. (M16A2, M16A4, and M4 Only) Determine if burst cam (12) and/or burst cam spring (11) is frozen or improperly assembled.
Disassemble, clean, lubricate, and reassemble correctly (WP 0023).
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9
1 1
1 0 1 2 9
1 0
M 1 6 A 2 , M 1 6 A 4 , a n d M 4 O n l y M 1 6 A 3 a n d M 4 A 1 O n l y Figure 8. Hammer and Burst Cam Inspection.
Step 6. Inspect for broken, defective, or missing firing pin retaining pin (13).
Replace firing pin retaining pin (WP 0011).
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1 3
Figure 9. Firing Pin Retaining Pin Inspection.
Step 7. Determine if selector lever (14) is frozen on SAFE position.
Disassemble and clean (WP 0021).
Step 8. Inspect for broken firing pin (15) or for firing pin that does not meet gage protrusion requirement.
Replace firing pin (WP 0011).
S A F E S E M I
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1 4 1 5
Figure 10. Selector Lever and Firing Pin Inspection.
6. FAILURE TO UNLOCK.
Step 1. Inspect for burred locking lugs on bolt assembly (16).
Remove burrs.
Step 2. Inspect for burred lugs (17) on barrel extension.
Remove burrs.
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1 6
1 7
Figure 11. Locking Lugs Inspection.
Step 3. Check for short recoil.
See Malfunction 10.
7. FAILURE TO EXTRACT.
Step 1. Inspect for defective extractor pin (18), cartridge extractor (19), and/or extractor spring assembly (7).
Replace extractor pin, cartridge extractor, and/or extractor spring assembly (WP 0012).
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1 8
1 9
7
Figure 12. Cartridge Extractor Inspection.
Step 2. Inspect badly pitted chamber with reflector tool (WP 0039, Figure 23, item 3).
Replace barrel assembly if chamber is badly pitted (WP 0015).
Step 3. Check for short recoil.
See Malfunction 10.
8. FAILURE TO EJECT.
Step 1. Inspect for broken cartridge ejector (22).
Replace cartridge ejector (WP 0012).
Step 2. Determine if cartridge ejector (22) is stuck in bolt body (20).
Disassemble and clean (WP 0012).
Step 3. Inspect for weak or broken ejector spring (21).
Replace ejector spring (WP 0012).
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2 0
2 1
2 2
Figure 13. Cartridge Ejector Inspection.
Step 4. Check for short recoil.
See Malfunction 10.
9. FAILURE TO COCK.
Step 1. Inspect for worn or broken trigger nose (24) or trigger spring (25).
Replace trigger (23) or defective trigger spring (WP 0024).
Step 2. Inspect for worn or broken hammer trigger notch (28).
Replace hammer (10) (WP 0021 and WP 0023).
Step 3. Inspect for worn or broken hammer disconnector hook (27).
Replace hammer (10) (WP 0021 and WP 0023).
Step 4. Inspect for worn or broken automatic sear hook (26).
Replace hammer (10) (WP 0021 and WP 0023).
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Figure 14. Trigger and Hammer Inspection.
Step 5. (M16A3 and M4A1 have only one disconnector) Inspect for worn or broken disconnector hooks (29).
Replace defective disconnectors (30) (WP 0021).
Step 6. (M16A3 and M4A1 have only one spring) Inspect for weak, broken, or missing disconnector springs (34).
Replace disconnector springs (WP 0021).
Step 7. Inspect for worn, broken, or missing automatic sear (33).
Replace automatic sear (WP 0021).
Step 8. Inspect for weak or broken automatic sear spring (32).
Replace automatic sear (33) (WP 0021).
Step 9. Determine if long leg (31) of automatic sear spring (32) is incorrectly assembled in receiver.
Remove automatic sear (33) and install correctly (WP 0021).
Step 10. (M16A2, M16A4, and M4 only) Determine if burst cam (12) or burst cam spring (11) is frozen or improperly assembled.
Disassemble, inspect, clean, lubricate, or replace as required (WP 0021).
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2 9 3 0
3 4
3 3 3 2
3 1 1 1
M 1 6 A 2 / 1 2 M 1 6 A 4 / M 4
M 1 6 A 3 / M 4 A 1 2 9
3 0
3 0 2 9
Figure 15. Disconnector, Automatic Sear, and Burst Cam Inspection.
Step 11. Check for short recoil.
10. SHORT RECOIL.
Step 1. Inspect for broken or damaged action spring (3).
Replace action spring (WP 0021).
Step 2. Inspect for unlubricated or dirty action spring (3) and receiver extension.
Clean and lubricate.
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3
Figure 16. Action Spring Replacement.
Step 3. Inspect for improper gap space or worn, missing, or broken bolt rings (35).
a. Stagger bolt ring gaps (approximately 1/3 turn apart).
b. If worn, broken, or missing, replace bolt rings and stagger gaps (WP 0012).
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3 5
Figure 17. Bolt Ring Gap Adjustment.
Step 4. Inspect for carbon build-up or foreign matter in narrow passage of bolt carrier key (5).
Clean with CLP (WP 0045, item 9) and a worn bore brush.
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5
Figure 18. Bolt Carrier Key Inspection.
Step 5. Inspect for broken or bent gas tube (8).
Adjust by bending in area of handguards or replace gas tube (WP 0015).
Step 6. Determine if gas tube spring pin (37) is missing from front sight (36).
Replace gas tube spring pin (WP 0015).
Step 7. Inspect for partially plugged gas system because of carbon build-up in gas tube (8).
Replace gas tube (WP 0015).
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8 3 6
3 7
10. SHORT RECOIL - Continued.
WARNING
CARBON REMOVING COMPOUND