A2 tower M4 flat top ?

[green grunt]

I have a A2 20" barrel with a non F marked front sight tower..
want to use a flat top receiver....M4 type, I read somewhere that you might need a taller front sight...true...false ??

[Oldmandan]

True

[CamW]

.040 taller

https://www.knsprecisioninc.com/product/square-072-front-sight-040-taller/

[ar15barrels]

I have a A2 20" barrel with a non F marked front sight tower..
want to use a flat top receiver....M4 type, I read somewhere that you might need a taller front sight...true...false ??

20" barrels are NOT supposed to have an F marked FSB.

F marked FSB is for carbine gassed barrels.

[ar15barrels]

True

False.

Only carbine barrels get the taller FSB.
It has nothing to do with the flattop vs A2 reciever.
This difference is to makeup for the additional drop and the different elevation turret values of a carbine vs rifle sight radius and velocity differences between the barrel lengths.

[green grunt]

Thanks All ...
....I have a Windhan Weaponry A2 Gvt 20" and the front sight tower is not F marked

I also have a PSA premium 20" the same configuration and it has a F marked front sight tower

why the difference...

[Oldmandan]

Thanks All ...
....I have a Windhan Weaponry A2 Gvt 20" and the front sight tower is not F marked

I also have a PSA premium 20" the same configuration and it has a F marked front sight tower

why the difference...

Because PSA...

I also have a rifle length PSA with F marked FSB. PSA is prob just ignorant to the information that Randal just laid out...

Who wants to volunteer to call and tell them?

Not it!

[M60A1Rise]

I have a Windhan Weaponry A2 Gvt 20"

I almost bought one of those.......TWICE But ended up not getting one , changed mind 1st time , 2nd time they sold out by the time I read the email from Atlantic.

[ar15barrels]

Thanks All ...
....I have a Windhan Weaponry A2 Gvt 20" and the front sight tower is not F marked

I also have a PSA premium 20" the same configuration and it has a F marked front sight tower

why the difference...

Because everyone THINKS they need an F marked FSB.
They sell what people want, even if it's wrong.

You can still USE an F height FSB on ANY barrel.
You just need to shorten the front sight post by 0.040" when an F height FSB is used on a rifle.
It's easier to shorten a front sight post than to extend one.

They also might be stamping an F on a rifle height FSB just to make people quit asking for the F stamped FSB...

I have run into F stamped FSB with both heights.
All that having an F stamped FSB REALLY means is that you have an F stamped on your FSB.