magpul mbus front sight adjustment problem.

Discussion in 'Optics / Sights / Lasers / Lights' started by gemini1960, Jul 17, 2015.

  1. gemini1960

    gemini1960 Member

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    I installed a longshot full length, 15.4 inch piticanny rail to the top of my highpoint 4095. I mounted a set of magpul mbus gen 2 sights on the rail. I have the sight pin adjusted all the way down to raise the impact point and it is still impacting 4 inchs low at 20 feet, any thoughts on remedying situation? I'm thinking of adding a .5 inch utg low riser to the rear mbus, not sure if I am looking at the sight geometry correctly, considered filing the front pin to achieve aim. Trying to avoid trip to the gunsmith, if I am missing something simple.
     
  2. talon

    talon the banned wagon

    Are you sure you have a matched set of sights?
    Seems like a stupid question but more than once someone has had an unmatching front and rear.
    How close do you have them mounted together? You'll want them as far apart as possible for best results.
    I use 45 degree offset sights on a full length rail and had zero issue setting them up.
    Post some pics maybe, makes it easier to help.
     

  3. I used the stock hi point fr sight and the mbus for the rear( had them on a dpms recon and never used them went to scope )
     
  4. ajole

    ajole Supporting Member

    34,524
    10,757
    NE Utah
    My guess is 20 feet is too close for carbine zeroing?

    With the sights high over the bore axis, there's a large angle in between line of sight (LOS) and bore axis.

    To make the bullet hit on your point of aim at 20 feet, that angle would be huge, the bullet would be launched like a football punt, it would be WAY too high at 25 and 50 yards or maybe even 100?

    Try 25 yards?

    Edited to add these diagrams

    [​IMG]
     
    Last edited: Jul 17, 2015
  5. talon

    talon the banned wagon

    I thought he said 20yards not feet, yea at 20 feet your better off using your carbine as a club. That's kinda pointless to try and zero at that distance.
     
  6. ajole

    ajole Supporting Member

    34,524
    10,757
    NE Utah
    The other question is, is the rear sight elevation adjustable?
     
  7. gemini1960

    gemini1960 Member

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    I had tried 50 feet and had a similar drop in aim point, set it up with a sig sauer red dot and it's dead on at any range, trying to set it up for redundancy. Red dot has a quick release, so I'd like to be accurate in the manual mode. I see what you are saying about the close range geometry. Sights are at opposite ends of the 15 inch rail. Same set up I see on alot of carbines on this sight.
    Going back to the range this weekend , I'll get it figured out. Appreciate the help.
     
  8. gemini1960

    gemini1960 Member

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    Also Ajole, the magpul rear sight is not adjustable for elevation.
     
  9. talon

    talon the banned wagon

    50 feet is still pointless. A carbine is not a 50 foot weapon. Buy a handgun or shotgun or throw a rock. Use the tool for what its intended for.
    Not only that but at 50 feet you better be damn sure of what's behind whatever your aiming at, because its getting hit too.
     
  10. ajole

    ajole Supporting Member

    34,524
    10,757
    NE Utah
    Come on Talon. Lots and lots, and lots of folks like the carbine for HD. The rest of it is true regardless of what you are shooting.;)



    Really, it is pretty odd that he's 4 inches low.

    Theoretically, it shouldn't be any further off than the distance between the sights and the bore. Meaning at HD ranges, you'd be 1-2 inches low, better than most could aim in the dark under stress.

    About the only way to get that low, is if the front sight were really, really too tall.


    Did the gun shoot right before the rail swap?
     
  11. planosteve

    planosteve Lifetime Supporter

    Zero for 50 yds and your sight will be ok. The sights are designed for the application you are attempting.
     
  12. MachoMelvin

    MachoMelvin Well-Known Member

    I had purchased from 2 different venders on ebay, the magpul mbus flip up sights. Both pairs were the knockoff Chinese kind, both were JUNK. I couldn't get either pair to sight in?
     
  13. gemini1960

    gemini1960 Member

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    Yes , shot fine. The dinamics of the large frame of the rear sight and ghost ring of the front messed with my visual focus.
    When I moved out to 50 ft the drop was.about 10 inchs. It shoots straight ahead, just the aim point is low. Like I said I think I can fix it by filing the front post a couple of mm , but leaving that as a.last resort. Likewise if the rear was adjustable for elevation it would not be an issue.
     
  14. ajole

    ajole Supporting Member

    34,524
    10,757
    NE Utah
    Wow...there's something wrong here.

    Did it shoot low with the OEM irons? If you didn't zero them before removal, I'd SERIOUSLY go back and zero them first, to make sure the gun is ok. BTW...I really don't get your point about the OEM sights and visual focus...the aperture sight is supposed to be the best for focus, the OEM system is similar to the high end target sights like the Palma systems, a circle inside a circle.

    Anywho...if the gun doesn't shoot too low with the OEM stuff, and can be zeroed...

    Is the new rail installed right?

    Is the new rail too high in the front somehow?

    Is the front sight properly seated in the slot?

    Not saying anything, just ensuring the bases are all covered.
     
  15. talon

    talon the banned wagon

    Ill say it Again, pictures will greatly help us to help you.
     
  16. USMC_VET

    USMC_VET Supporting Member


    Yes pics will help alot !!

    Also make sure you mount is sitting securely onto the rail
     
  17. Have a set of Green Blobs and the same issue with the front sight being too long. Cannot turn it down far enough and the sight itself becomes locked in the up position. Before I buy a fully adjustable rear sight, I also wonder if a .5 or .7 riser might be the answer. Is it a waste of time?
     
  18. JoeP

    JoeP Member

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    I didn't see anywhere in this thread if the height of the front and rear sight were measured to see if they were the same. I understand those measurements should be 1.44" or 35.5mm as in the picture. I don't have a 4095 and my 4595 front sight has been removed so I don't know what the height of the OEM front sight is.

    My backup iron sights measure exactly 1.44" front and rear.

    Joe P
     

    Attached Files:

    Last edited: Feb 18, 2017
  19. ajole

    ajole Supporting Member

    34,524
    10,757
    NE Utah
    Is your front sight perhaps the type designed to fit on a reduced height gas block, instead of a rail?

    What is the height from the flat that rides on top of the rail, to the tip of the post?
     
  20. Nope. The front rail mounted flip up is simply too high compared to the original factory sight mounted on the end of the barrel. The post cannot be lowered enough. It is indeed a rail mounted sight made for an AR.