Quantcast
  1. Sign up now and join over 35,000 northwest gun owners. It's quick, easy, and 100% free!

AR-15 Sight Alignment Question

Discussion in 'Rifle Discussion' started by disintegratinglinks, Nov 23, 2014.

  1. disintegratinglinks

    disintegratinglinks Seattle Member

    Messages:
    31
    Likes Received:
    8
    Hi There,

    I was hoping someone can help figure out what's wrong with my AR-15.

    My rear sight needs to be way to the right in order for the gun to be on target at 100 yards. I don't understand why this is. I stuck a long, tight-fitting wooden dowel down the barrel in order to test if my front sight is aligned with my receiver. I'm not sure, but it looks like it is not straight.

    Maybe the front sight base is not aligned.... but that seems unlikely, since it is held in by two taper pins. The two pins automatically align the base as I understand it.

    It could be that the barrel is not indexed with the receiver. Or it could be that the detachable carry handle is not properly aligned—but the handle is tightened down nicely.

    Should I just send this to a gunsmith to analyze and fix it?

    Thanks for your responses.
     
    Last edited: Nov 24, 2014
  2. IronMonster

    IronMonster Washington Opinionated Member Diamond Supporter

    Messages:
    4,185
    Likes Received:
    6,659
    First thing I would do is find another rear sight and see where it zeros.

    And just because the front sight base is pinned does not mean it is pinned clocked correctly. I have seen more than one that was canted.
     
  3. disintegratinglinks

    disintegratinglinks Seattle Member

    Messages:
    31
    Likes Received:
    8
    Thanks IronMonster. Since posting I have done more research on this topic. I'm thinking that my FSB might be canted, due to me removing the FSB in order to install a free-float handguard.

    I'm going to use a leveling procedure to check my sight alignment tonight.
     
  4. coop44

    coop44 Tacoma ,WA Well-Known Member

    Messages:
    2,606
    Likes Received:
    984
    Colt "aligned" such problems by smacking the barrel with a lead babbit. first check the sight alignment with the bore "picture" Mk 1 eyeballs will tell you how far off you are. Secure the upper to a fixture (I use a sawhorse), sight through the center of the bore ( circle in a circle) centering the bore on a predetermined point on a vertical surface (spot on the wall). Next, check your sights, if they are not centered left to right on ther same spot you next need to determine where the proble lies. this method will also give you an idea of how far you are actually off. if things do line up, you may have nothing more wrong than a damaged crown.
     
    IronMonster likes this.
  5. Capn Jack

    Capn Jack Wet-Stern Washington Bronze Supporter Bronze Supporter

    Messages:
    1,764
    Likes Received:
    1,845
    If it was OK before you took it apart.....:rolleyes: Saying goes....

    If you're not a part of the cure....You may be part of the problem.;)
     
  6. disintegratinglinks

    disintegratinglinks Seattle Member

    Messages:
    31
    Likes Received:
    8
    True, it was fine before I took it apart. But it was a stock AR-15. That's like a barbie doll with no cute outfits.
     
  7. Capn Jack

    Capn Jack Wet-Stern Washington Bronze Supporter Bronze Supporter

    Messages:
    1,764
    Likes Received:
    1,845
    Then go back over your assembly and find out where it went sour.:rolleyes:

    Did you have to force something?:confused:
     
  8. coop44

    coop44 Tacoma ,WA Well-Known Member

    Messages:
    2,606
    Likes Received:
    984
    What manner did you use to remove the front sight base? did you lay the barrel on a wooden block or otherwise back it up? Did you clamp it in a barrel vise and drive the pins out? If so you may have actually tweaked the barrel.

    It doesn't take much force to put a slight bend on the end of the barrel. looking below at how much it is off, I suspect it may be what happened in your case.
     
    Last edited: Nov 25, 2014
  9. rick benjamin

    rick benjamin USA, Or, Damascus Secure the drama Silver Supporter 2016 Volunteer

    Messages:
    2,436
    Likes Received:
    2,774
    My M4 with Troy also.
    I could shim the right side of the rail where the rear sight grips (need 0.047" shim, piece of beer can?)
    could remove 0.047" from the right side of where the front sight post grips the gas port rail
    upload_2014-11-24_18-17-50.png
     
  10. mjbskwim

    mjbskwim Salmon,Idaho Well-Known Member

    Messages:
    10,414
    Likes Received:
    7,663
    It's been years since I played with tapered pins,could he have put them back incorrectly?
     
  11. coop44

    coop44 Tacoma ,WA Well-Known Member

    Messages:
    2,606
    Likes Received:
    984
    nope they only go in one way. As an experiment years ago I drilled the pin holes out straight and used roll pins. It worked . don't recall what size they were though, sorry. It would be one way to correct a canted sight.
     
    Last edited: Nov 25, 2014
  12. Mr Smith

    Mr Smith 54 68 65 20 73 74 69 63 6b 73 Active Member

    Messages:
    190
    Likes Received:
    59
    Definitely not a fan of gas block front sights...

    however you can try to eyeball it as best you can to straighten it out and make sure you don't bind the gas tube or miss align the gas port.

    A bore sight can be helpful in making sure you are on target without firing a shot. check your sights vs the laser and try to get that front sight lined up with the rear sight zeroed.

    as far as the carry handle goes: as long as it is completely attached to the upper receiver, and not any forward rail, then it should lock onto the rail at zero. if it doesn't, then it was poorly made.

    My Iron sights on my free floating setup are both clamp on and the sights are dead on with zero adjustments. no gunsmith was involved with it either...

    That being said, I tend to think you have that gas block on slightly crooked. or you just have a poorly made carry handle.. but if it was on target before you took it apart...I tend to think you have the gas block on crooked.
     
  13. eldbillbo

    eldbillbo clackamas New world samurai and a redneck none the less Bronze Supporter

    Messages:
    3,170
    Likes Received:
    885
    remove your taper pins and re install in a different order with the one that goes in the easyist first put that one all the way in then check it and install the other if still over go in reverse order

    you may not have them installed the same depth as the original not that matters that much but may be the cause

    A armorer friend use to just hit it with a rubber mallet to get them to align after reinstallation i wouldn't advise it tough