moving from an A2 upper to a flat top upper: Questions.

AR-15 » AR Discussions

AR Sponsor:

[ARCHIVED THREAD] - moving from an A2 upper to a flat top upper: Questions.

Posted: 9/9/2005 10:52:54 AM EDT

I'd like to change my stock A2 build to a flat top build. I just want to replace the carry handle A2 upper with an A3 or A4 upper. Is there anything I need to know before making the swap? I will be having a gunsmith actually do the swap for me, but are there any problems I may run into in changing the upper?

Also, what is the difference between an A3 and A4 stripped upper?

Thanks for the help.

Posted: 9/9/2005 11:01:21 AM EDT

[#1]

AFAIK A3 and A4 uppers should be the same.

btw,some say you need a F marked front sight post.

Posted: 9/9/2005 11:04:31 AM EDT

[#2]

No problems. Very easy job. It should not take more than 20 min. What kind of upper and barel? The A-3 is the colt designation for the flat top. The A-4 is i belive the milatery designation. No real difence. You will find adding a optical or electonic sight much simpler. Have fun.

Posted: 9/9/2005 11:09:51 AM EDT

[#3]

No difference between A3 & A4, read this post

Posted: 9/9/2005 11:31:09 AM EDT

[#4]

I have an Olympic Arms kit around a RRA stripped lower. Everything works great, I just want to move to a scope and don't like the mount for the carry handle. Is this something I could do at home? I put everything together on the rifle, except the upper came complete. Would I need to get a head space gauge?

thanks for all the quick replies.

Posted: 9/9/2005 11:32:46 AM EDT

[#5]

check out the build it yourself section and the tacked threads there for all the instructions

Posted: 9/9/2005 11:50:30 AM EDT

[#6]

The headspace is set in the barrel and doesn't change so you don't have to worry about that. If you use a backup iron sight your front sight post will be too low. You'll either need to replace the FSB with an "F" one (hard) or replace the sight post with the Bushy .040" taller one (easy but cheesy).

Posted: 9/9/2005 12:12:33 PM EDT

[#7]

will the front sight post be in the way of the scope?

Posted: 9/9/2005 12:14:11 PM EDT

[#8]

Quoted:
The headspace is set in the barrel and doesn't change so you don't have to worry about that. If you use a backup iron sight your front sight post will be too low. You'll either need to replace the FSB with an "F" one (hard) or replace the sight post with the Bushy .040" taller one (easy but cheesy).

Oh, i thought you only needed to replace the FSB or for that matter the front sight post if you were using the ARMS40 BUIS. What's the deal?
I'm using a GG&G buis on a flat top Colt upper scoped with an ELCAN, and i don't think i'll ever use it, but it feels good to have it there just in case. Question being, am i gonna need this F marked FSB or the taller post IF i ever need to use my BUIS? dunno? maybe? YES? you're gonna have to find out for yourself?

thanks
HUNTER.

[ARCHIVED THREAD] - moving from an A2 upper to a flat top upper: Questions.

AR-15 » AR Discussions

AR Sponsor:

Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.

Warning

Confirm Action

About AR15.COM

Stay Connected

Newsletter

Contact Us