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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
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.
Link Posted: 9/9/2005 11:01:21 AM EDT
AFAIK A3 and A4 uppers should be the same.

btw,some say you need a F marked front sight post.
Link Posted: 9/9/2005 11:04:31 AM EDT
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.
Link Posted: 9/9/2005 11:09:51 AM EDT
No difference between A3 & A4, read this post
Link Posted: 9/9/2005 11:31:09 AM EDT
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.
Link Posted: 9/9/2005 11:32:46 AM EDT
check out the build it yourself section and the tacked threads there for all the instructions
Link Posted: 9/9/2005 11:50:30 AM EDT
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).
Link Posted: 9/9/2005 12:12:33 PM EDT
will the front sight post be in the way of the scope?
Link Posted: 9/9/2005 12:14:11 PM EDT
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