just got a eotech 517 for my birthday couple weeks ago,thought i could mount on my colt a2 carry handle  (arms a2 plus mount) but unfortunately does not co-witness at all w/ the standard a2 style front and rear sights. so,.......have changed the plan up a little (much to my wife's chagrin) to buy a complete new flat top upper in 5.56 w/the standard a2 front sight post and all the other options that i liked on my colt 6530 upper. okay,so the question is: will i have a lower 1/3rd. co-witness w/my raised base 517 and using the matech rear buis? i let a co-worker take my eotech 517 home w/ him to try it on his flat top upper and he came back into work the next day and drew me a picture of what he had seen thru my eotech.....and it sure sounds as though it's a lower 1/3rd. i have yet to buy my new upper as i'm still price shopping for exactly what i want.thanks for any/all  replies.

The 517 (or any raised base EO, for that matter) will always be a lower 1/3 co-witness with a standard height base or flattop.....Not a fan

well hell,i'm just glad i'm hopefully gonna get a lower 1/3......i bought it w/the intention of being somewhat hampered to access the controls on the other models,so i opted for the side activated buttons. woulda,coulda,shoulda......

btw,thanks for the info. if  you dont mind me asking,what is your reason for your particular opinion?

I actually like the lower 1/3 with an EOTech. I have an XPS2-0 which is not set up like your 517. I had to buy a YHM riser for it. It's all personal preference.

I have my eotech with the co witness.  The only reason I have it set up for it is because I have folding sights.  I
could not have done it any other way.  I would have problems looking at the dot and then the sights.
I would have had to do the lower cowit if I had non folding sights

My 511 and the 512 have true cowitness on the Colt 6920 flat top.  I can't imagine it would be different, but I have been wrong before.

thing is the 511 and the 512 dont have the added 7mm riser on them as does the 516,517,and the 557.thats why my friend at work could'nt understand the lower 1/3 co-wit that he was seeing w/ my 517 on his flattie upper. he's used to the absolute co-wit and hadnt ever seen it before. i'm just glad i'll get a lower 1/3rd,i'd hate to put out the bread for a new upper only to find it still would'nt  co-wit. anyone using the matech buis w/their eotech's?

Here a pic of my 517 on an M&P15T

pc it looks as though you have a absolute co-wit going there......or is it just the camera angle? what kind of forward sight are you running?