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Need AR15 Wisdom

Discussion in 'Gunsmithing and Repairs' started by Murphster, Nov 20, 2006.

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  1. Murphster

    Murphster Member

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    Just got a new Bushmaster carbine (14.5 in. barrel.) It's my third AR. This one is having reliability issues. Problem is probably an extraction problem. I'm getting the bolt back with a loaded round under the spent casing problem. During the first 50 rounds this happened about every 3rd or 4th shot. Disassembly, break-in, lubrication on ejector, etc. has gotten the problem to once every 50 shots. This isn't a cleaning or lube problem. My feeling is that the extractor just occasionally lets go of the case when it's about 95% extracted, then moves forward, stripping off a fresh round. Would a Wolf replacement extractor spring help? Could this be a break-in issue. Only have about 150 rounds through it. (Previous AR's were very reliable from the time they were new.) Would a new Colt carbine extractor fit my Bushmaster carbine? Thanks in advance for any help. All rounds were Winchester 55 grain white box.
     
  2. jungle

    jungle Member

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    Extractor springs and spring buffers(that little blue or black thing in your extractor spring) are very important. Check and replace if needed. It is a good idea to check the gas rings and key for proper fit and also that the extractor itself has no wayward roughness.
    A good thing to do is remove the extractor and break the edges on either side where it grasps the rim, this will cut down the brass flakes getting into the action. The ejector can also be removed and the forward edge broken to smooth things up.
    Try a different type of ammo, although WWB runs well in most guns a new one may require a little more snap. Slather the oil on until things smooth out.
     
  3. kaferhaus

    kaferhaus Member

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    What you describe is usually an ammo problem. 2nd bet would be a weak buffer spring
     
  4. Murphster

    Murphster Member

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    Thanks for the input. I've got a new, stronger extractor spring and buffer on order from Brownell's. Also have a supply of Federal ammo to try as soon as the Brownell items arrive.
     
  5. khadre

    khadre Member

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    What everyone mentioned, especially underpower load from factory ammo, above but:

    if it's extracting and letting the brass case off too early, you might wanna try an O-ring around the extractor spring like the o-rings from "Crane", Defender D-ring from MGI, or #60 heat resistant O-ring from your local hardware store (this is what I use since the first 2 cost way more).

    Because this sounds like there is not enough force for the extractor to maintain the grip on the case rim until the bolt and case sufficiently clears the chamber to throw the case out of the way. The O-ring multiplies this force.

    You can get the $1 Crane O-ring from www.adcofirearms.com. It's in the middle of the homepage with explanation.

    NOTE: I would advise to NOT use both the Wolff X-power extractor spring together with the O-ring; use the Wolff xpower spring by itself with the orginal extractor insert or the other O-ring around original extractor spring (I would favor the O-ring combination) but not both Wolff Xpower Xtractor spring and O-ring together as that puts too much pressure on the brass rim and and ripping the case rim off the case, leaving you with a stuck case in the chamber. (This you will need a .223 case extractor to pull out or cleaning rod pushed from the muzzle end).

    This is assuming you have a nice clean and lightly lubed chamber to begin with to minimize other possible factors.
     
  6. Murphster

    Murphster Member

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    Thanks Khadre. Received and installed the extra power Wolfe extractor spring yesterday. It's definitely stronger than the one they came with the Bushmaster. Haven't had the chance to try it out yet. If it doesn't do the trick, I'll order the O ring.
     
  7. 1911Tuner

    1911Tuner Moderator Emeritus

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    AR-15

    SHort cycle can cause some of the things that you described.

    Have you checked to see if the screws that hold the bolt carrier key are tight? Staked correctly? Key gas hole plugged or misaligned? Kink or blockage in the gas tube?
     
  8. khadre

    khadre Member

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    Forgot to add, what 1911Tuner mentioned above checked those areas of the gas key.

    *Screw down the gas key screws tightly
    *Make sure you have strong staking marks on both sides of screws on the gas key.
    (You know you have strong staking marks when the metal eats a little into the recessed hex-shaped screws.)

    Please do follow up and let us know how it all turns out.
     
  9. Murphster

    Murphster Member

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    Just back from the range. Don't know if it was different ammo (Federal American Eagle instead of Winchester white box) or the new, heavier Wolfe extractor spring, but the rifle functioned perfectly through 60 rounds. I know 60 rounds (all I had on hand) isn't a definitive test, but it's never gone that long without a problem before. So with cautious optimism, I think it's fixed. Again, my thanks for the help, suggestions, and insights.
     
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