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 F-Marked vs Standard Front Sight Bases
JohnCeglarek  [Member]
5/24/2007 2:46:05 AM EST
OK, I know I'm asking a question that's probably been answered many times, but I can't find the information.

What is the difference between an F-marked front sight base and a standard front sight base, and when do you use one vs the other?

Thanks,

John
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MaddMan  [Member]
5/24/2007 2:48:39 AM EST
F Marked = Use with Flat top
Standard = A1/A2 upper
F marked are just a little taller.

If you use a standard with a flat top you may need a taller front sight blade.
JohnCeglarek  [Member]
5/24/2007 2:59:33 AM EST
F-marked = any flat top, or just a carbine...and why? If you have a detachable carry handle on a flat top, what is different about it that you need a different sight base?

And, other than the F-mark, what are the height differences between the two?

Thanks,

John
jmart  [Member]
5/24/2007 5:02:24 AM EST
My guess is they are within .040" of each other because the taller post that Bushmaster sells for use in non-F marked FSB's is that much taller than a regular post.
Alpha-Romeo3  [Team Member]
5/24/2007 5:42:09 AM EST

Originally Posted By JohnCeglarek:
F-marked = any flat top, or just a carbine...and why? If you have a detachable carry handle on a flat top, what is different about it that you need a different sight base?

And, other than the F-mark, what are the height differences between the two?

Thanks,

John



Picture posted by members in previous threads about the difference of F FSB and standard A2 FSB

The F marked (or sometimes unmarked) FSB are used in both rifles and carbines by the military, Colt and some manufacturers.

The rear sight height of the detachable carry handles are the same as fixed and folding rear back up iron sights (BUIS).

When they designed the flat top the sight height was increased upwards to .040" therefore they have to increase the shelf of the F FSB the same amount.
CoffeeAddict19  [Member]
5/24/2007 6:40:06 AM EST
This is what it looks like...

F-Marked Base
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