new build, having issues

Discussion in 'AR-15 Discussion' started by boudmanj, Mar 5, 2013.

  1. boudmanj

    boudmanj New Member

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    Just built an ar, mmc lower, brass forged aluminum upper, not sure of the manufacturer of the bolt, 14.5 in barrel, bc1.5 comp, h3 buffer, gun fires fine, but will either jam or won't pick up the next round after ejecting, thought it was a mag issue but ran multiple different styles and still won't function properly...thinking gas tube issue

    Has anyone experienced this, can you help
     
  2. kytowboater

    kytowboater Active Member

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  3. boudmanj

    boudmanj New Member

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    That's one of my options, I have a heavy in another gun I built as well, but the tolerance isn't as tight one my first build
     
  4. purehavoc

    purehavoc New Member

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    This ^^^^^ Its way to heavy for a 14.5" IMHO unless it over gassed , I run a 3.8 oz buffer on a 14.5" PSA , I had a 4.2 and a 4.0 oz in it and it ran fine but it wouldnt keep the bolt open after the last round . Thats where I would start, in all honesty take a carbine 3.0 oz buffer out of another gun and try it first and see if it runs , Bet ya it runs perfect :D
     
  5. Sgt_Skrb_25

    Sgt_Skrb_25 New Member

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    I was all excited because I knew the answer. Feel like the kid in class who knows the answer so i raise my hand, and someone beat me to it. That buffer is way to heavy. I only run a H2 in my 7.5" barrel.lighten it up and see what happens.
     
  6. SSGN_Doc

    SSGN_Doc Well-Known Member

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    Heavy buffer is a possibility. Could also be a gas issue. If the gas key on the bolt carrier does not appear to have gas escaping from under the gas key you could make sure the gas block is in the right position on the barrel. If you used a bolt on gas block it is fairly easy to push it took far to the rear and partly block the gas port. There should be a slight gap between the shoulder on the barrel and the rear if the gas block.
     
  7. boudmanj

    boudmanj New Member

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    Thanks everyone, that makes sense with the shorter barrel, its my first short barrel, I will try a lighter one and report back in a day or so
     
  8. boudmanj

    boudmanj New Member

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    The gas block is a factory a2, my other option would be the tube, thanks again
     
  9. purehavoc

    purehavoc New Member

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    dont even mess with anything until you try a standard carbine buffer , 110% guarantee that will fix your problem.

    Also what is a brass forged aluminum upper ? :D
     
  10. boudmanj

    boudmanj New Member

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    Sorry got my words jumbled, its the square manufacturers marking from bafe
     
  11. Quentin

    Quentin New Member

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    Yes, Brass Aluminum Forging Enterprises. They use the square forge mark and produce nice receivers. By chance all of my uppers (BCM, Daniel Defense and PSA) are theirs.

    Do you have cabine length or midlength gas? H3 definitely is too heavy for 14.5" midlength. Often is ok for carbine length if you don't use low powered ammo. A lot of real M4s have the H3 but of course they use NATO powered rounds and are carbine length 14.5".
     
  12. AgentTikki

    AgentTikki New Member

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    Started off with a H3 buffer eh?

    FIRST Go with Purehavoc's suggestion and use a standard carbine buffer first.

    Have you tried, just loading one round in a mag, and seeing if the bolt locks back after you shoot it? What kind of ammo are you using? Have you tried M193 or M855 5.56 x45 nato with the same results?
     
  13. boudmanj

    boudmanj New Member

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    I run the same buffer in my other ar, no issues, its definately not the buffer, had my gas tube checked out, its bad and my gas key is off centered, on top of everything else, I have a bum gas block

    In 8 1/2 yrs as an 0311 in the usmc, I've never come across this problem, I'm not sure how to properly stake a gas key or even if I really need to change it
     
  14. AgentTikki

    AgentTikki New Member

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    If your gas key is bad, your gun won't cycle. If your gas block is leaky, your gun won't cycle. Those are pretty significant failures.
     
  15. boudmanj

    boudmanj New Member

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    That seems to be the general consensus at the local gun shop, I know where I can get a block and tube, the gas key may be a hard, I'm anxious to get this thing up and running
     
  16. purehavoc

    purehavoc New Member

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    if your gas key is off center it will damage the gas tube , if it cycles without damaging the gas tube I would leave it alone, take the key off, get new grade 8 bolts , torque to the proper specs and stake it . what kind of upper do you have ?
     
  17. boudmanj

    boudmanj New Member

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    Bafe upper, bushmaster bcg, apparently the bcg is almost 5 yrs old and has a couple hundred rounds through it, can't see that being a problem though, I've put hundreds of thousands of rnds down range and never bent a gas key, I am going to track one down though and not a take a chance in messing up a new tube
     
  18. purehavoc

    purehavoc New Member

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    Did u try the buffer change.?
    When u put the gas key on put a little bit of lock tite between the key and carrier and let dry over night this will help seal it also. Here's what I have noticed taking stuff to a shop and this doesn't qualify for all shops. #1 most of them around here know very little about ARs as far as fixing a problem or tuning . 9/10 times you spend money with their fixes that never fixes it.
    If you have a problem and bring it to the boards listen to what people are telling you and try the stuff that doesn't cost u a ton of money.
    I build my own buffer weights for each gun I own I have 2 16" identical barrels ,same manufacturer, same twist same every thing . One runs a 4.4oz buffer. The other chokes all over its self with any thing more than a 3.8 oz buffer.
    Another thing I would do is make sure you have the proper length buffer spring in it.
     
    Last edited: Mar 7, 2013
  19. boudmanj

    boudmanj New Member

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    Tried three different buffers, same result, my gas block leaks, carbon on the hand guards, and I just found out my gas tube is bad from the guy I got it from, didn't pay anything for it thank god