Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
AR Sponsor
Yesterday 4:38:04 PM EDT
Do I need a special front sight post using an M16A1 upper receiver with an "F" marked front sight base on an 11'5" barrel?  Will I want to lower the post into the FSB or raise it up high?  Is it possible to use the post that came in the Colt Commando 11.5" barrel or do I need a taller or shorter one?  Thanks.  I don't have all of the parts in my hand yet.
Yesterday 4:46:33 PM EDT
[#1]
The F marked front sight base is made to work with a flat top upper receiver.  I see no mention of which upper receiver, so if you are mounting the barrel on a  flat top upper receiver, then the answer is that you should be good to go.

If you are using a F marked front sight base barrel, and mounting it on a A1 or A2 carry handle type upper receiver, then you may find that the front sight base may be too tall when trying to get it zeroed, and may need a shorter front sight post.


CY6
Greg Sullivan "Sully"
WeaponsArmorer
SLR15 Rifles
Defensive Edge Training
(763) 712-0123
Yesterday 5:44:04 PM EDT
[Last Edit: airgun1][Edited] [#2]
I specified M16A1 upper.  I am not aware of any M16A1 flat top receivers.  Thank you for the information.  That is what I needed.
Yesterday 6:50:44 PM EDT
[#3]
The F marked front sight base is .040" taller as compared to the traditional front sight base.  



CY6
Greg Sullivan "Sully"
WeaponsArmorer
SLR15 Rifles
Defensive Edge Training
(763) 712-0123
Yesterday 8:48:02 PM EDT
[#4]
Originally Posted By airgun1:
Do I need a special front sight post using an M16A1 upper receiver with an "F" marked front sight base on an 11'5" barrel?  Will I want to lower the post into the FSB or raise it up high?  Is it possible to use the post that came in the Colt Commando 11.5" barrel or do I need a taller or shorter one?  Thanks.  I don't have all of the parts in my hand yet.
View Quote


I've used a couple 11.5 Newer Colt Commando barrels with F marked FSBs on retro builds with A1 uppers and they zeroed just fine at 50 yards, the front sight was a little lower than on the 20"bbl A1, but not really noticable.

Sign up to continue the discussion

Create a free account to share your thoughts, follow topics, and connect with the AR15.COM community.

Already a member? Sign In

AR Sponsor