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AR15 failing to fully chamber

Discussion in 'Maintenance & Gunsmithing' started by OregonPlinker, Oct 24, 2012.

  1. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    This is a new gun. Well now it has 360 rounds fired through it. I thought it just needed broke in till I noticed some marks on my casings. After noticing these marks I went and shot a 30 round mag through it and paid more attention to what was going on.

    It doesnt start failing to chamber till it blows the oil out of the chamber. The first time I shot it I got like 37 rounds down range before failure. Today it was like 5.

    These scratches are on all the casings even when the gun is dripping oil. Some are worse than others especially the ones that dont chamber all the way. The scratches start on the shell about 3/8" down from the shoulder and continue for about 1/4". They stop almost exactly half way between the shoulder and the base of the shell. When the round is in the chamber the scratches go from 12:eek:clock to 3:30 maybe 4:eek:clock. Its hard to see that area of the chamber since I cant find my handy little mirror but I think I see a little "ridge" in there...

    It seems that the rounds coming out of the left side of the magazine are the ones that stick. Out of the 30 rounds I really paid attention to what was happening. 6 of them failed to fully chamber. All from the left side of the mag. I only tested on one mag out of 4. But failures are consistent in all the mags.When the gun is cool I might get 10-15 rounds down range. Sometimes Ill get 5-7 rounds down range sometimes only 3. The warmer the gun the more failures happen.Sometimes when I pull the trigger the bolt slams the rest of the way shut and sometimes it doesnt.

    Its a S&W so its under warranty but I dont know how long they will keep it and if its as simple as I think it is Ill just smooth it out myself. This is my first AR so I dont know if this behavior is normal. It doesnt seem that way. My new 1911 leaves very similar marks on the brass but it doesnt jam every 3 shots. Ive never had this much trouble out of a gun. New or used... What do you guys think? Thank you for reading my mile long post!
     
  2. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    Can you post a picture of the feedramps?

    Also, stop shooting it with oil in the chamber, I dont want to hear about you going to the hospital.
     
  3. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Eh. I hate trying to post pics on forums. Never have succeeded. Ill try to figure it out. It might take me a while...lol
     
  4. 142

    142 Rogue Valley Member

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    That's the magic formula to display a photo. No spaces!
     
  5. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Ok here go's nothing. Its kinda hard to get good pics of the feed ramps. We'll see how they look on here...

    262.jpg

    263.jpg

    265.jpg
     
  6. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Dont mind the q tip fuzz
     
  7. nubus

    nubus Guest

    Have the headspace checked with gauges by person who knows how to use them. As long as it's not chrome lined you should be able to ream or polish the chamber if there is a chamber issue. However, the NUMBER ONE CAUSE of this type of issue is ammunition. What ammo are you using?
     
  8. ridnjon

    ridnjon vancouver wa Active Member

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    How about some pics of the casings too? Headspace needs to be checked. But sounds like it needs to be reemed or chamber cleaned, or polished.
     
  9. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    Feed ramps look correct. Is it steel cased ammo?
     
  10. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    When this happens, especially with the marks you describe, it's a high probability that there is some roughness in the chamber. On the chance that it's just stuff stuck to the surface of he chamber from one of the numerous finish operations in the factory, get a chamber brush and go to work. Scrub the dickens out of the chamber. You may also try some J-B Bore paste on a patch wrapped around a brush or better yet, a 30 cal bore mop. This is a non-embedding polishing compound that won't "grind" on the surface but will remove any paint, parkerizing, or other bits and pieces that may be stuck in the chamber. On some firearms I have even cut a slit in a piece of dowel, put some 1500-2000 grit wet/dry sandpaper in the slit, and using a cordless drill, polished out the chamber.

    These weapons are mass produced. They're tested with just a few rounds, if at all, not several magazines full of ammo.

    When I buy or build the first thing I do is clean the chamber and if there's the slightest sign of any parkerization, paint, dirt, in the chamber, I clean it out. Have even bought a couple where I had to polish the feed ramps, matching them to the adjacent ramps in the upper (M-4) to make them feed properly. Kind of the difference between a $800 firearm and a $1500 one.
     
  11. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Ive only shot UMC through it so far. Ill shoot cheap but I wont shoot steel case. Its a S&W Sporter M&P15. So its the bottom of their barrel...

    I cleaned it before I shot it and didnt notice any thing funny. Ive cleaned I 3 other times now and no difference. I made a "feeler" and can feel roughness on that side of the chamber compared to the other areas. I soaked some patches in break free and am letting it sit for a bit the Ill give it a little scrubbing. I'll see how it feels after that. If that doesnt fix it Ill send it back to S&W. They need to know about this kind of stuff I think. Who knows.
     
  12. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    I just put 30 rounds through it from 2 different mags. 25 rounds in a row with no jams. The 26th round stuck and the last 4 went fine. The marks are non existent on some cases and less dramatic on others. The one that stuck is typical of previous marks. Ill get some pics up while Im letting it soak again. It did seem to do better though.
     
  13. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    020e.jpg

    These are shells I just ran through the gun. The cleaner the gun the less the marks but the crud has to be building up on something I think...

    020e.jpg
     
  14. Blitzkrieg

    Blitzkrieg WA Well-Known Member

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    You got a bad chamber with a rough patch..send it back. And stop shooting guns with oil in the chambers.. store them that way and run a dry patch thru before you shoot
     
  15. Velzey

    Velzey Estacada, Oregon Gunsmith Gunsmith Bronze Vendor Bronze Supporter

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    Oh yah send it back to Smith, with a few of those empties! That chamber has a bad spot in it...
     
  16. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Ok, Thanks guys
     
  17. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    You mentioned that it was Smith's "Economy Model". That usually means that there was a minimal amount of clean up and testing after tested.

    If you want to go to the expense of sending it back, by all means that is your prerogative.

    What I see on those cases is something that could well be fixed by at the least wrapping some steel wool around a bore brush, enough for a fairly snug fit in the dhamber, put the bore brush on a length or two of GI cleaning rod, chucking in a Cordless drill, and cleaning it out.

    Your choice but from what I see on the cases it's not that big an issue. Even some paint residue can be hammered into a hard coating and make marks like that on a case. Steel wool will clean it out. Dry or with some hoppe's on it, either way, but I'd try that before I ran to UPS to ship it back to S&W.

    Have you contacted S&W yet? Send them an e-mail at qa@smith-wesson.com. They may have a solution for you but regardless you need to contact them so they can send you a shipping label if you want them to pay for the freight.
     
  18. Blitzkrieg

    Blitzkrieg WA Well-Known Member

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    I would want a new barrel, personally
     
  19. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    I emailed them last night for the shipping label. The marks have gotten less with different cleaning methods. But surely havent gone away. I havent tried anything on a drill yet. I may do that this afternoon. Do you know how long it usually takes to get guns back from warranty service?
     
  20. OregonPlinker

    OregonPlinker Creswell, Or Active Member

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    Thats kind of what I was thinking...