Gas Block

Discussion in 'Black Rifle Forum' started by skeeter7, Oct 14, 2012.

  1. skeeter7

    skeeter7 Brass Vulture

    I am interested in converting the standard front sight on my Colt 6720 to a gas block which would accept a flip up sight in the front. I am not sure what to get or what is recommended for the lightweight profile barrel of the AR6720. I would essentially like to have a front sight I could use with my removable carry handle or switch out to a rear flip up sight if I plan to ever use a scope or holographic sight. Any help and recommendations would be appreciated. Thanks!

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  3. are you looking for a gas block with a rail or just a low profile gas block that can be mounted under a free float? Daniel Defense had a decent low profile gas block that will fit under rails for the light weight barrel. There are others out there also with rails on them (yankee hill). Just remember that the rail will get hot if you do alot of shooting so a metal flip up sight would need to go on it.

  4. Cole125

    Silver Member

    Just for your information, you CAN use a scope or red dot sight on a rifle with a fixed front sight. With a magnified optic over 4x or so the front sight will not be visible at all.

    That said you can swap the fixed front sight base, for a low profile gas block with a rail fairly easily.

    This is what you want, clamp on low profile gas block w/rail on top for gas block height folding front sight.|Inside%20Diameter_1=xzzx625/Product/AR-15-M16-GAS-BLOCK

    edit; you want a .625 gas block for a skinny barrel.
    #3 Cole125, Oct 14, 2012
    Last edited: Oct 14, 2012
  5. Don't ruin your Colt w/ a railed gas block. That's so Bushmaster, lol. Take a dremel to the OE front post and make a low-pro GB. It's a much better option than any set-screw GB.
  6. skeeter7

    skeeter7 Brass Vulture

    Not sure to be quite honest. If I get an optic for it, it would most likely be something like the Aimpoint Pro. Looking for opinions on the best way to set my rifle up for that. I thought I would need to eliminate the fixed front sight post in order to do that. I'm still learning here...
  7. skeeter7

    skeeter7 Brass Vulture

    Something scares me about taking a dremel tool to my new rifle...:rofl: Never heard of that before. Guess I'll have to do some research.
    #6 skeeter7, Oct 14, 2012
    Last edited: Oct 14, 2012
  8. faawrenchbndr

    faawrenchbndr DirtyThirty fan

    Leave the Colt alone, reason to change the gas block for
    Aimpoint use.
  9. mvician

    Lifetime Member

    This ^

    don't butcher your Colt, leave the FSB as it is for either a magnified optic or a red dot.
  10. NeverMore1701

    NeverMore1701 Fear no Evil
    Platinum Member

    I vote to leave it alone. If you want to put a longer rail or something that actually requires a low profile gas block, shave your FSB. A few minutes will net you this:



    Plus however long you want to spend prettying it up. I didn't worry about making it too perfect looking, as it's under the handguard. This way is cheap (free), easy, quick, and avoids the problems of a set screw or clamp on block.
  11. Cole125

    Silver Member

    A Aimpoint works just fine with a fixed front sight. The dot just sits above the front sight post.
  12. Another vote for leaving the front sight alone. No need to change it.
  13. OP, were you wanting to add a longer rail or just concerend about the FSP getting in the way?
  14. If you want a FSB that flips down, PRI makes a pretty hot one, IMO.
  15. Hour13

    Hour13 Tah-dah!

    My question too.

    OP, if you aren't wanting to add an extended handguard, don't worry about the sight up front just leave it alone.

    When running that PRO, you'll be sighting with both eyes open. Right eye sees the dot, wrong eye sees the target, your brain puts the two together. Put dot on the target, pull trigger. You'll never even notice the front sight. This is also why these optics can still be used, even with the front cover closed.

    Because the "co-witness" on my CompM2 is in the lower 1/3rd, I don't even use a flip-up on the rear sight on my Beater AR. Iron A2 front sight, Daniel Defense fixed rear sight.

    When shooting in very bright sunlight, I leave the front cover on, makes the dot easy to see, even on low-power settings.

  16. skeeter7

    skeeter7 Brass Vulture

    Thanks so much for the fast replies everyone! :wavey:

    I was just concerned about the front sight post getting in the way. I'm fine with the rail length as I run a KISS setup and only have a Magpul AFG2 attached to my quad rail right now. I like the way it looks with the factory FSP and would rather leave it alone instead of butcher it but I thought for sure it wouldn't work with an optic attached to the rifle because of other setups I have seen out there with flip up front sights. I guess you do learn something everyday. I will leave my Colt untouched in that aspect then. The 6720 came with a Matech rear flip up sight. Should I run that when I run an optic or is there something else I should be looking at when I take my carry handle off for use when I run the Aimpoint?
  17. mvician

    Lifetime Member

    The MaTech is fine.
  18. Leave it then. If you're not wanting a longer rail there's really no reason to mess w/ anything.
  19. The Pirate

    The Pirate HARRRRR!!!

    Scopes will generally see through front sight posts and red dots look over them. You'll forget it's there in a week.

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