Troubleshooting a previously working rifle
Bolt assembly fails to lock rear after firing last round
| Inspect | Remedy |
| Dirty or corroded bolt latch | Clean. |
| Inspect for restricted movement of bolt catch | Disassemble and clean |
| Inspect for broken bolt catch | Replace bolt catch |
| Inspect for weak or broken bolt catch spring | Replace bolt catch spring |
| Inspect magazine follower | Replace magazine |
| Determine if magazine spring is weak | Replace magazine |
| Inspect magazine feed lips for bends or breaks | Replace magazine |
| Determine if follower binds during operation | Replace magazine |
Bolt Carrier Hangs Up
| Inspect | Remedy |
| Round Jammed between bolt and charging handle and / or double feed. | Remove magazine, push on bottom of bolt latch, bang rifle butt on the ground bolt should lock to rear. Round should fall through bottom of magazine. |
Bolt Wont Unlock
| Dirty or Burred Bolt | See gunsmith |
Double Feed
| Inspect | Remedy |
| Dirty or Burred Bolt | See gunsmith |
Double Firing
| Inspect | Remedy |
| Perform function test | If fails, continue with troubleshooting otherwise hold rifle securely against shoulder when firing. |
| Inspect for worn or broken trigger notch of hammer | Replace hammer |
| Inspect for worn or broken disconnector hook of hammer | Replace hammer |
| Inspect for worn hammer or trigger pin hole | Replace lower receiver |
| Inspect for defective semi-automatic disconnector | Replace semi-automatic disconnector |
| Inspect for worn or broken trigger | Replace trigger |
Failure to chamber
| Inspect | Remedy |
| Dirt, corrosion or carbon buildup in barrel locking lugs | Clean lugs |
| Carbon in chamber or on gas tube | Clean. |
| Inspect for weak or broken action spring | Replace action spring |
Failure to cock
| Inspect | Remedy |
| Inspect for worn or broken disconnector hook | Replace disconnector |
| Inspect for weak broken or missing disconnector springs | Replace disconnector springs |
| Inspect for worn or broken hammer trigger notch | Replace hammer |
| Inspect for worn or broken hammer disconnector hook | Replace hammer |
| Inspect for worn or broken trigger nose or trigger spring | Replace trigger or defective trigger spring |
| Check for short stroking | see short stroking troubleshooting |
Failure to eject
| Inspect | Remedy |
| Determine if ejector is stuck in bolt body | Disassemble and clean |
| Inspect for broken ejector | Replace ejector |
| Inspect for weak or broken spring | Replace ejector spring |
| Check for short stroking | see short stroking troubleshooting |
Failure to extract
| Inspect | Remedy |
| Fouling or carbon in extractor recess or lip | Clean |
| Carbon In Chamber | Clean Chamber |
| Frozen Extractor | Remove and Clean |
| Restricted buffer assembly | Remove and clean |
| Restricted movement of bolt carrier group | Remove, clean and lube. Make sure gas tube fits freely into carrier |
| Broken Extractor Spring | Replace |
Failure to feed
| Inspect | Remedy |
| Magazine not fully seated | Adjust mag catch or reseat |
| Determine if magazine catch is out of adjustment | adjust magazine catch |
| Dirty Magazine | Clean |
| Defective Magazine | Replace |
| Inspect for defective magazine catch | Replace magazine catch |
| Inspect for weak or broken magazine catch spring | Replace magazine catch spring |
| Check for short stroking | see short stroking troubleshooting |
| Action of buffer assembly is restricted | Take out buffer and spring and clean |
| Too Many Rounds In Magazine | Take out excess |
Failure to fire
| Inspect | Remedy |
| check for improper assembly of hammer spring | assemble properly |
| Too much carbon on firing pin or in firing pin recess | Clean |
| Determine if selector lever is frozen in safe position | Disassemble and clean |
| Selector Lever on Safe | Put it on Fire |
| Defective Ammo | Remove and discard |
| Inspect for carbon buildup | remove cartridge extractor and clean |
| Inspect for broken firing pin | Replace firing pin |
| Inspect for broken or missing firring pin retaining pin | Replace firing pin retaining pin |
| Inspect for broken hammer | Replace hammer |
| Inspect for broken hammer spring | Replace hammer spring |
| Improper Assembly of firing pin | Retaining pin goes n back of large shoulder of firing pin |
| Too Much Oil In Firing Pin Recess | Wipe clean with pipe cleaner |
Failure to lock
| Inspect | Remedy |
| Inspect for improperly assembled extractor spring assembly | Assemble correctly |
| Inspect for loose screws on bolt carrier key | Reassemble using new screws |
| Inspect for weak or broken action spring | Replace action spring |
| Inspect for missing bolt cam pin | Replace bolt cam pin |
| Inspect for damaged bolt carrier key | Replace bolt carrier key |
| Inspect for bent gas tube | Replace gas tube |
| Check for short stroking | See short stroking troubleshooting |
Failure to unlock
| Inspect | Remedy |
| Inspect for burred locking lugs on bolt assembly | Remove burrs |
| Inspect for burred lugs on barrel extension | Remove burrs |
| check for short stroking | See short stroking troubleshooting |
Fires with selector on safe or when trigger is released with lever on semi
| Inspect | Remedy |
| Inspect for defective selector | Replace selector |
| Inspect for worn or broken rear portion of trigger | Replace trigger |
Hammer pin walks
determine if it walks or works loose during firing or of hammer pin is very easy to push out of recever when hammer is installedReplace hammer assembly| Inspect | Remedy |
Magazine Won’t lock in rifle
| Inspect | Remedy |
| Possible dirty or corroded magazine catch | Disassemble and clean |
| Inspect for worn or broken magazine catch | Replace magazine catch |
| Inspect for defecctive magazine catch spring | Replace magazine catch spring |
Rifle can not be zeroed
| [Windage] determine if barrel assembly is out of alignment with rear sight on upper reciever | Align barrel and upper receiver assembly |
| [Elevation] Inspect for defective front sight | Remove front sight post, if damaged and Replace |
| [Elevation] Inspect for defective rear sight | Repair as required |
| Inspect for defective or bent barrel assembly | Replace barrel assembly |
Selector Lever Binds
| Dirt or sand under trigger | Clean |
| Needs oil | Lubricate |
Short Stroking
| Inspect for broken or bent gas tube | Adjust or Replace gas tube |
| Carbon or dirt in carrier | Clean |
| Inspect for carbon build up in barrel gas port | Clean |
| Inspect for unlubricated or dirty action sprint and receiver extension | Clean and lubricate |
| Inspect for carbon buildup in gas key | Clean and lubricate |
| Inspect for broken or damaged action spring | Replace action spring |
| Inspect for partially plugged gas system because of carbon buildup in gas tube | Replace gas tube |
| Determine if roll pin is missing from gas block | Replace roll pin |
| Inspect for improper gap space, worn missing or broken gas rings | Stagger gas ring gaps, if worn broken or missing Replace gas rings and stagger gaps |
| Gaps in gas rings | Stagger ring gaps |