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Thread: Colt M4 Carbine 6920 front sight removal

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    Colt M4 Carbine 6920 front sight removal

    I recently purchased my first AR and was curious on how difficult it would be to remove my front iron sight. Not only would I like to add a 9.5" quad rail but also would like flip up iron sights. I'm new to this hobby so any help would be appreciated. I've added photos of the AR below. Thanks in advance!






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    Everyone will say search it...there is a mountain of information on this.

    Typically, especially for BCM FSB, they are no fun to remove.

    This is what I learned: You need two people, a big hammer, and proper oversized punch. And HIT the pins out.

    Nice color on the AR, BTW.

    Here is a video, this guy is removing the FSB on his Colt.

    http://www.youtube.com/watch?v=uS0J3pRcNus
    Last edited by Zane1844; 04-23-13 at 22:35.

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    Welcome and excellent choice on your first AR. Using the orange search button in the upper right will likely answer most of your questions. With the right tools, removing a front sight base is pretty simple.

    Most people here will advise you to shoot your gun as is and worry about mods or upgrades later. Do you know what all is involved when installing a free float rail that extends beyond the gas block?
    A.A.S. Mechanical Engineering Technology

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    Quote Originally Posted by Zane1844 View Post
    Everyone will say search it...there is a mountain of information on this.

    Typically, especially for BCM FSB, they are no fun to remove.

    This is what I learned: You need two people, a big hammer, and proper oversized punch. And HIT the pins out.

    Nice color on the AR, BTW.

    Here is a video, this guy is removing the FSB on his Colt.

    http://www.youtube.com/watch?v=uS0J3pRcNus
    Thank you for the reply, I suppose I will have to do some more research before I commit to installing a new rail. The MOE guard is just too small for my liking so I was looking for something larger. I found a Daniel Defense AR Lite 9.5 FSP rail that appears to fit around the front iron sight but if removing the sight isn't too hard, I would lean towards doing that and adding flip up sights.

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    My advice is to get a Centurion Arms Carbine Cut Out rail or the 12" FSP rail if you are set on a rail system and adding more length. I do not advise removing the FSB and installing a low pro block.

    Seeing that you are new most of this process will not be easily accomplished without proper tools and knowledge. Installing either of those rail above can be accomplished by simply cutting part of the Delta ring assembly away.





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    Quote Originally Posted by Eric D. View Post
    Welcome and excellent choice on your first AR. Using the orange search button in the upper right will likely answer most of your questions. With the right tools, removing a front sight base is pretty simple.

    Most people here will advise you to shoot your gun as is and worry about mods or upgrades later. Do you know what all is involved when installing a free float rail that extends beyond the gas block?
    Thank you for the reply and information on the search button. My brother is the one who got me interested in purchasing an AR and he told me that exact thing. (Shoot it as is before buying/adding mods)

    As far as my knowledge regarding what is involved in installing a free float rail that extends beyond the gas block, I have none. The MOE guard feels too short when holding the weapon and I was looking for something a little longer. Either removing the front iron sight and adding a 9.5" rail or leaving the sight and adding a rail that goes around it.

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    Quote Originally Posted by Iraqgunz View Post
    My advice is to get a Centurion Arms Carbine Cut Out rail or the 12" FSP rail if you are set on a rail system and adding more length. I do not advise removing the FSB and installing a low pro block.

    Seeing that you are new most of this process will not be easily accomplished without proper tools and knowledge. Installing either of those rail above can be accomplished by simply cutting part of the Delta ring assembly away.
    Thank you for the reply, is this the rail you are suggesting?

    http://www.centurionarms.net/index.p...art&Itemid=177

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    OP, you will need the following: Torque wrench, Brownells Action Black, I suggest the PRI Barrel Nut Wrench, some kind of grease (I used Moly grease without graphite) punches, and a hammer. Oh and a Breaker bar to remove the factory Barrel nut, and a correct size wrench to remove and install the flash hider if you do not get the multi tool.

    http://www.brownells.com/gunsmith-to...prod22385.aspx

    http://www.brownells.com/gunsmith-to...prod27412.aspx

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    Quote Originally Posted by Zane1844 View Post
    OP, you will need the following: Torque wrench, Brownells Action Black, I suggest the PRI Barrel Nut Wrench, some kind of grease (I used Moly grease without graphite) punches, and a hammer. Oh and a Breaker bar to remove the factory Barrel nut, and a correct size wrench to remove and install the flash hider if you do not get the multi tool.

    http://www.brownells.com/gunsmith-to...prod22385.aspx

    http://www.brownells.com/gunsmith-to...prod27412.aspx
    Appreciate the info as well as posting the links directly.

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    If you still want to go this route (I recommend putting some rounds through it first), and you don't want to buy all the tools to do it yourself, Adco can cut down the FSB. They do a very good job and have a fast turn around.

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    Since youre new to ARs, i say shoot it, learn it and then change stuff out as you discover needs/preferences. Nothing more expensive than buying parts to address a perceived need, only to later buy more parts to address actual needs.
    Great weapon choice btw!

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    Appreciate the advice everyone. So far the only thing I have purchased other than the weapon and ammunition, is the EOTech EXPS2-0 HOLOgraphic sight. I will probably hold off on buying anything until I actually get a chance to shoot. Here are the things I have been considering as of now, any advice on these would also be appreciated.

    Daniel Defense AR15 Lite Rail 9.5 FSP, Carbine (If I remove the FBS, AR15 Lite Rail 9.0)
    Troy Folding BUIS (Front and rear if I remove the FBS)
    Surefire or Streamlight weapon light (Not sure which is preferred)

    I may also switch out some of the Magpul MOE equipment for other Magpul accessories, for example I like the MIAD pistol grip more than the MOE.

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    If you are going to go to all the trouble removing or cutting down the FSB (I would cut before removing...research "shaving FSB" ) you might as well as go all the way and get a 12" rail.

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    Quote Originally Posted by AKDoug View Post
    If you are going to go to all the trouble removing or cutting down the FSB (I would cut before removing...research "shaving FSB" ) you might as well as go all the way and get a 12" rail.
    Shaving doesn't look too difficult, about how far would the barrel stick out with a 12" rail? I don't have the gun in hand at the moment otherwise I would just measure, I don't know the weapon specs off the top of my head either.

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    It'll stick out plenty, somewhere around 5". A 12" handguard is pretty much the most common free float on a 16" barrel. I happen to like the fixed front sight, though, and I would take Iraqgunz advice and go with the Centurion C4 FSP rail. You won't need any special tools to mount it.... instructions here... http://www.centurionarms.net/images/...ms_C4Rails.pdf
    Last edited by AKDoug; 04-24-13 at 01:38.

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    If you don't have a second person to help, a vise or C-clamp helps considerably in loosening up the FSB taper pins before you start hammering away with the punch. I destroyed the pins and a punch the first time I removed the pins, but on the second rifle I did it to, it went fairly easily with using a vise to push the pins first.

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    Quote Originally Posted by AKDoug View Post
    It'll stick out plenty, somewhere around 5". A 12" handguard is pretty much the most common free float on a 16" barrel. I happen to like the fixed front sight, though, and I would take Iraqgunz advice and go with the Centurion C4 FSP rail. You won't need any special tools to mount it.... instructions here... http://www.centurionarms.net/images/...ms_C4Rails.pdf
    Thanks for the info, as far as FSP type rails, I would probably stick with the 9.5" because I don't really like a top rail past the FBS.

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    Quote Originally Posted by IZinterrogator View Post
    If you don't have a second person to help, a vise or C-clamp helps considerably in loosening up the FSB taper pins before you start hammering away with the punch. I destroyed the pins and a punch the first time I removed the pins, but on the second rifle I did it to, it went fairly easily with using a vise to push the pins first.
    Appreciate the heads up!

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    Do not remove the a2 fsb IMO.

    Simply change out the magpul guards for a VLTOR CASV-EL drop in free float rail that will give you your extended hand purchase area, free floating, and absolutely no modification.

    I have and use the CASV-S and it is a great product. Rigid and completely free of crap, err rails, unless you install them yourself, wherever you want them.

    Caveat: Your magpul rear folding buis will either need to be filed a bit to fit behind the casv-el, or replaced for a Troy rear folding buis (which are also fantastic quality sights).

    ETA LINK:
    http://www.vltor.com/casv-sub.htm
    Last edited by ColtSeavers; 04-24-13 at 01:55.

  20. #20
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    The rail beyond or past the FSB serves a purpose. It's to mount a light at 12 o'clock which is the most preferential location for a number of reasons. I suggest that you take a while to read and understand the system more.

    Quote Originally Posted by ColtM4Carbine View Post
    Thanks for the info, as far as FSP type rails, I would probably stick with the 9.5" because I don't really like a top rail past the FBS.





    "A firearm should be considered a fighting weapon first. Any other use should be considered a bonus." -Me

    Click here for Semper Paratus Arms AR15 armorer schedule/locations.

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

    Multiple armorer certifications

    I am affiliated and work with SIONICS Weapon Systems in Tucson, AZ

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