Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 30

Thread: What are the causes of a double feed

  1. #11
    Join Date
    Aug 2006
    Location
    Colorado
    Posts
    823
    Feedback Score
    0
    Quote Originally Posted by HES View Post
    Thanks. Her stance wasn't bad, but it wasn't great either. So that is something I worked with her last night.


    Once round gets partially fed into the chamber, the second one follows it and gets the bullet portion wedged between the bottom of the top round and the top of the chamber / ramp. This is an illustration I just whipped up that shows whats happening.



    Normally I'd agree with you but this one has me stumped. Only the one type of ammo double feeds. Its got me scratching my head unless it is the ammo.
    I've not had that type of double, but that's better than the type where the round gets jammed in the gas tube.

    Either way I'd say it's the mag 99% of the time like others have said. But to have one type of ammo do it and another not sure is different. I'd go with measuring the ammo like has been posted......

  2. #12
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,900
    Feedback Score
    104 (100%)
    How about this. Go to the local gun store, find a PMAG for about 15.00, buy it and see if it continues.



    Owner/Instructor at Semper Paratus Arms

    Facebook: https://www.facebook.com/SemperParatusArms/

    Semper Paratus Arms AR15 Armorer Course http://www.semperparatusarms.com/cou...-registration/

    M4C Misc. Training and Course Announcements- http://www.m4carbine.net/forumdisplay.php?f=141

    Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com

  3. #13
    Join Date
    Jun 2006
    Location
    SE FL
    Posts
    14,147
    Feedback Score
    5 (100%)
    Mark/number all of your magazines so that you can ensure that it really is just the one type of ammo.

    If you can take the same magazine, as verified by numbering, and get a DF with the GA ammo but feed fine with known quality ammo, and can get a DF in multiple magazines with the GA but feed fine with known quality ammo, then I'm stumped.


    Sometimes it's just bad juju. I'm sure there's a scientific/mechanical/chemical/otherwise logical and rational explanation, but I really can't think of a reason for the type of double you describe that would be ammo related.

    Just think about what's happening. I'm assuming she's able to chamber and fire the first round just fine, and it's the second (or subsequent) round that's causing the double. In that case you're getting two bullets looking for the same hole. The only way for that to happen is for two bullets to be getting stripped out of the magazine.

    Now go look at a loaded good condition magazine. How the hell do you get two rounds out of that badboy at one time?

    When you say "US GI 30 and 20 round types", we're not talking surplus are we? We're talking magazines from D&H or similar that you bought NIW, right?

  4. #14
    Join Date
    Feb 2008
    Location
    Tampa Bay Area
    Posts
    2,006
    Feedback Score
    1 (100%)
    Quote Originally Posted by rob_s View Post
    Mark/number all of your magazines so that you can ensure that it really is just the one type of ammo.

    If you can take the same magazine, as verified by numbering, and get a DF with the GA ammo but feed fine with known quality ammo, and can get a DF in multiple magazines with the GA but feed fine with known quality ammo, then I'm stumped.


    Sometimes it's just bad juju. I'm sure there's a scientific/mechanical/chemical/otherwise logical and rational explanation, but I really can't think of a reason for the type of double you describe that would be ammo related.

    Just think about what's happening. I'm assuming she's able to chamber and fire the first round just fine, and it's the second (or subsequent) round that's causing the double. In that case you're getting two bullets looking for the same hole. The only way for that to happen is for two bullets to be getting stripped out of the magazine.

    Now go look at a loaded good condition magazine. How the hell do you get two rounds out of that badboy at one time?

    When you say "US GI 30 and 20 round types", we're not talking surplus are we? We're talking magazines from D&H or similar that you bought NIW, right?
    For the magazines the three 30 round magazines were bought within the last 9 months and have either the green magpull follower or the gray one from Anvil Arms. Of the 20 round magazines, I had to borrow them, but they appear on inspection to be in good condition and are relatively new looking. When I spoke to the guys who lent them to her they said that they didn't have any problems to report. As she reported to me, once she switched to the GA, that's when the problems started, regardless of the magazine used. Trust me, I'm stumped too.

  5. #15
    Join Date
    Jun 2006
    Location
    SE FL
    Posts
    14,147
    Feedback Score
    5 (100%)
    you're definitely going to have to get out and test this one yourself.

  6. #16
    Join Date
    Dec 2006
    Location
    N. Alabama
    Posts
    2,048
    Feedback Score
    8 (100%)
    Quote Originally Posted by HES View Post
    ...either the green magpull follower...
    Did Magpul followers ever come in green?

  7. #17
    Join Date
    Aug 2008
    Posts
    453
    Feedback Score
    0
    Did the bolt damage the lower round at all? I'm having a similar problem with a close to brand new 6920 and would appreciate any advice.

    The gun is somewhat dirty - approximately 400 rounds without cleaning, other than wiping the carbon off the bolt and bolt carrier. the gun was well lubricated and I was using P-mags and 62 grain green-tip ammo from ammo-man. the double feed (two live rounds trying to feed together) happened twice, once with a 30 round p-mag and (i believe) once with a 20 round p-mag. both mags are new and have had been used once or twice with no problems.

    both times in my gun, the bolt lugs dug deeply into the round just south of the case shoulder. i've fired about 600 rounds of this particular batch of ammo with no problems in this and an S&W M&P 15, but knowing where it came from i'm not going to absolve the ammo yet...

  8. #18
    Join Date
    Sep 2007
    Posts
    1,105
    Feedback Score
    0
    I'm having the same issue with close to new CMMG middy 16" (mostly PP ammo)...attempting to double feed and also failures to eject, then the next round jams into the spent case. Once was a big PITA: stuck between the bolt and end of CH. This is with a BCM bolt and pmags, so I didn't expect problems related to those.

  9. #19
    Join Date
    Feb 2008
    Location
    Tampa Bay Area
    Posts
    2,006
    Feedback Score
    1 (100%)
    I havent had the chance to get back to the range with my lovely bride and her (now) rifle to determine which round was being damaged. I did ask her and she can't remember. I may try to get to the range next week but if I don't then the next chance I'll get to go to the range will be in March (surgery coming up on the 5th that's gonna ground me for three months)

  10. #20
    Join Date
    Oct 2008
    Posts
    110
    Feedback Score
    7 (100%)
    Almost always magazine related.

Page 2 of 3 FirstFirst 123 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •