Converting to flat top

Discussion in 'AR-15 Discussion' started by Kdub, Feb 28, 2012.

  1. Kdub

    Kdub New Member

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    I have a dpms ap4 with removable carry handle and a front post sight. I'm trying to remove the front post so I can mount buis instead. I've googled and youtubed looking for help. Anyone done this before. I'm wondering mostly about what you do with the gas tube as it appears it is mounted into the post. Any ideas?
     
  2. canebrake

    canebrake New Member

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    Actually the gas tube and the sight tower are attached to the gas block.

    I think you would be better off buying a complete flat-top upper.

    And jump over to the Introduction section and say hi.
     

  3. jgand72

    jgand72 New Member

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    I have been thinking about getting rid of the front sight post as well.

    Can I replace the front sight post/gas block with a low profile gas block? It just seems too simple. Can anyone offer an explanation here?:confused:
     
    Last edited: Feb 28, 2012
  4. JonM

    JonM Moderator

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    The only danger is smacking the pins too hard and bending the barrel. There are delrin type blocks that arent terribly pricey that support the barrel and fsb for driving the pins out safely. They typically go left to right if im not mistaken.

    The two drift pins are tapered one side is wider than the other so have to be knocked out in a specific direction.

    You can do it if your super careful without a block but its like a three handed job.

    Installing a low profile gas block is very easy.

    That being said... there is no real reason other than looks to get rid of the fixed fsb. Any magnified device the fsb will disappear in your view. For 1x devices most people like it there for lower 1/3 cowitness
     
    Last edited: Feb 28, 2012
  5. mjkeat

    mjkeat New Member

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    Do you have a dremel? Remove the OE hand guard and gas tube then get to making a low profile gas block out of the existing one. It's easy and pinned on is better than a replacement set screw block.
     
    Last edited: Feb 28, 2012
  6. hmh

    hmh New Member

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    Knock the pin out that holds th sight on. Pinch the sight between two blocks of wood in a vise wd-40 the barrel. Set a block of wood on the muzzle and hit it. The gas tube will come out with the front sight post. I find it easier to pull the gas tube after the sight is off. Installing a new one make sure your holes are lined up I use compressed air to gauge when they are perfectly lined up.
     
  7. AgentTikki

    AgentTikki New Member

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    There is a lazy cheapo (!me!) alternative.

    I used a dremel to cut the front sight off, and grinded it smooth. without removing the front sight post. Special care must be taken to not cut too low into the gas block portion of the front sight post. (its not hard to figure out) There are many youtube vids on this, and it was a simple and free option (if you already have the tools)

    I used some black rattle can brake pint to touch up the newly exposed metal and never looked back. Tho the touch up really isn't too necessary if you put a rail or handguard over your new low pro gas block. You can't even see it with a handgaurd or rail covering it.

    Bonuses!

    +1 cheap
    +1 don't have to remove it first (lazy)
    +1 your new low profile gas block is pinned (good)
    +1 fast! (relative)
    +1 cheap!
    +1 you did it yourself!
    +1 did i mention it was cheap?
     
  8. AgentTikki

    AgentTikki New Member

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    ya what MJ said.... >.<
     
  9. Quentin

    Quentin New Member

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    To the guys who want to remove the standard FSB... Why? You should have very clear cut reasons before doing this. Not saying it's wrong to do for certain applications but usually is not necessary.
     
  10. mjkeat

    mjkeat New Member

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    True, nothing makes a better low profile gas block like a shaven FSP.
     
  11. Kdub

    Kdub New Member

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    My reason for wanting to do it is that I don't want my front sight cowitnessed in my red dot all the time. I find it distracting. I would rather have magpul flip up buis for when I need them and have a clear field of view when using just the dot. I was thinking about takin a dremel too it myself. I'll have to strip it down and take a look. Thanks for the replys.
     
  12. jgand72

    jgand72 New Member

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    I have a Bushnell Holosight I wish to put on when I get home from school in a few weeks. I just have a feeling that that I won't like the cowitness of the front sight and optic. Just trying to weigh the options.
     
  13. Quentin

    Quentin New Member

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    I'd sure give it a try first, you may find you like it just fine. I do. Also if you go with a bottom 1/3 cowitness you can flip down the rear BUIS and the dot tends to float above the front post which I don't find distracting.
     
  14. jgand72

    jgand72 New Member

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    I was actually going to ask about the 1/3 cowitness. This may be a stupid question, but bear with me here: With a 1/3 cowitness, do I have to look through the rear buis to aim properly, or can I line up well enough looking through the lens of the holosight?
     
  15. ZombieKiller83

    ZombieKiller83 New Member

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    I have mine set-up where it co-witnesses right smack dab in the middle but with the rear sight flipped down, the front post is a non issue to me, sometimes forget it's there :D
     
    Last edited: Feb 29, 2012
  16. ZombieKiller83

    ZombieKiller83 New Member

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    When you're using optic, your rear sight should be flipped down and you use the optic's reticle for target aquisition. Your buis is for that situation where your optic goes down during a course of fire and you need a quick solution to stay on target so you would flip your rear up and use the irons.
     
    Last edited: Feb 29, 2012
  17. jgand72

    jgand72 New Member

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    So, with a 1/3 co witness, would I zero the optic and irons for the same distance or different distances?:confused:
     
  18. ZombieKiller83

    ZombieKiller83 New Member

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    That would be your decision to make. You can zero either one at whatever distance you prefer as one does not rely on the other. 1/3 co witness means that while your optic is attached to the gun, the irons will be visible through the bottom 1/3 of the optic which would mean that if your optic were to go down in the middle of a firefight, you would not be required to remove the optic in order to use the iron sights allowing for a very quick transition to stay in the fight. Do you need co witnessed buis, no. Do you need buis at all, no but is it a good idea on both accounts, absolutely. Unless you plan on trusting your life to your rifle, I'd say you could skip the buis if don't want to deal with it.