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11/4/2005 1:11:37 PM EDT
Recently I had  a carbine rebuilt by an excellent local gunsmith.   I swiitched from an A1 configuration which zeroed easily to a flattop where I had a problems zeroing, almost running out of upward turns on the front sight and had to crank the Eotech's elevation alot to get a zero.
Components in my case are a Oly/SGW lower mounting a Bushmaster 16"patrolman's barrel (no marking on FSB), White oak armament flatop upper, BMAS flipup BUIS, and EoTech 552,  I'm former Infantry, so i know what a sight picture should look like and the fact that both the BUIS and EoTech both shot high leads me to believe its a build issue.   What issue would cause the weapon to shoot high?
11/4/2005 3:41:07 PM EDT
[#1]
what is the height of the flattop?
11/4/2005 4:40:53 PM EDT
[#2]
Thanks for your reply; I don't have a calpher, but I measured 1 and 11/16 inches from bottom of upper receiver to bottom of rail.
11/4/2005 6:22:20 PM EDT
[#3]
if that number is accurate then your upper is the problem

ar15.com/forums/topic.html?b=3&f=118&t=240120
the upper should be +/- 1.720"
11/4/2005 10:38:16 PM EDT
[#4]
I re-measured using the picture from your posted link as reference (again without calphers), and I got 1 and 11(1/2)/16th inches.  If my math is right that translates to 1.71875 inches, which is slightly below the numbers posted on the link.  I've replaced the front sight post with a taller (.40) post and if this don't work, I guess I'll have to try a elevation adjustable BUIS.  I guess EoTech will work as adjusted.  Thanks for the help, at least I now know  the problem is not related to the build.  Any other suggestions on correcting this issure would be appreciated.
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