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AR-15 Front Sight & "F" Height with which Rear Sight?

Discussion in 'Rifle Country' started by dust_101, Jul 16, 2007.

  1. dust_101

    dust_101 Well-Known Member


    Hopefully not asking to many AR questions on here, but posting on ar15.com has gotten slow responses, you all here on THR are much quicker on the draw :)

    For my build I'm planning to go with a standard GI fixed front sight w/o bayonet lug, and for the sake of being able to add/remove options a flattop upper. For the standard iron sight setup, do I need to locate a specific front sight base to match up with the standard removeable carry handle with rear sights? Is this what the "F" stamped front sights were intended to be used for?

    I've looked at the fold-down front sights, but for my needs I plan to be putting on a higher power scope for any benchrest shooting this rifle, and using iron sights 90% of the time, possibly putting a red-dot ACOG style for 3-gun....
  2. revitup

    revitup Active Member

    "F" sights are slightly lower for use with carbine length barrels (16").
  3. dust_101

    dust_101 Well-Known Member

    nuts... going for the 16" CAR barrel too... guess I'll need to find a "F" marked one to get the proper sight picture....
  4. Dave Markowitz

    Dave Markowitz Well-Known Member

    I am pretty sure this isn't correct. F-type sight bases are for use with flat top uppers.
  5. DMK

    DMK Well-Known Member

    The 'F' type sight base is slightly taller. It's not due to the barrel length. It due to the carry handle. When Colt designed the M4s for the military, they made the carry handle sight sit slightly higher. All carry handles since follow these specs. M16A4s (20 inch barrel) also have 'F' height front sight bases.

    1) It's not necessary with a fixed carry handle.

    2) It might not even be necessary with a removable carry handle. If you need to adjust your front sight post way up to zero, Bushmaster makes a taller front sight post for just this reason.

    Most AR15s have standard height front sight bases regardless of barrel length or whether they are a flat top or not. Only a few companies even make barrels with 'F' type front sight bases (Colt and CMMG are two).
  6. dust_101

    dust_101 Well-Known Member

    Thanks DMK that makes sense...

    ...now to just find a standard FSB that doesn't have a bayonet lug, gotta love NY
  7. Onmilo

    Onmilo Well-Known Member

    565-000-007 Carbine front sight .375" $14.50 taller front sight post for use on 10" to 16" barrel carbines with standard sight tower.

    This should solve your dilemma.
    Incidently,, Tijicon and Meprolight tritium front night sight posts are also taller than standard front sights and you won't need to locate an F marked front sight tower with these either
    Come to think of it, I don't ever recollect seeing an F marked front sight tower without a bayonet lug, not sure you could even buy one.

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