AR15.Com Archives
 eotech - why the riser?
at4rxj  [Team Member]
6/3/2009 7:47:02 PM EST
I have an eotech 511, and have been ok with it so far. A buddy of mine wants to buy it, and I have been eying the new 516 with the 123 batteries (or the 517 and run lithium aa's, but kinda prefer the slightly smaller 516).

Anyway, I happened to re-read the description, and saw it has the riser built in.

I ask first of all why, and second (mainly), do I have an alternative? Do the newer eotechs that have the 123 battery mounted transversely have this riser?

I have never understood the "lower 1/3" co-witness. What advantage does it give you other than the sight picture? I would much rather the lower profile and ability to "double check" your zero...

Anyway, not trying to rant or start an argument about that, I just wish they offered this as an OPTION, not as a fixed deal...

Should I go back to an aimpoint? I have my 1 aimpoint and 1 eotech, and I kinda like having one of each... However, I would like to stick with the true co-witness if at all possible.
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ChinoUSMC  [Team Member]
6/3/2009 7:55:27 PM EST


With the standard EOTech (w/out the riser), the placement of the ghost ring (when looking through it) would place it in the middle of the screen.

With the riser, it slightly raises the EOTech. That would place the ghost ring on the bottom edge of the screen, giving you more sight picture.


SuperSet72  [Team Member]
6/3/2009 8:08:46 PM EST
Supposedly, the new XPS models are absolute co-witness but they're not out yet. All the other new EOTech models are 1/3 cowitness with integral riser, which likely reflects the preferences of most shooters (including myself).
puskrat  [Life Member]
6/4/2009 8:06:06 AM EST
Originally Posted By at4rxj:
"lower 1/3" co-witness. What advantage does it give you other than the sight picture?



What is the advantage to that sight picture?
skipsan  [Team Member]
6/4/2009 8:12:26 AM EST
I've tried the Eotech both ways––riser and no riser. Determined that the no-riser was the preferred solution for me, and ditched the riser.
Strictly personal preference––there is no "right" way. Having the red dot/circle in the middle of the Eotech field of view is a little distracting at first but I quickly got used to it. Lighter, cheaper, one less connection to come loose.
AZ-AR15  [Team Member]
6/4/2009 9:36:11 AM EST
I have a LaRue Riser with my 552 primarily so that my Aimpoint magnifier will work with it too.
m24shooter  [Team Member]
6/4/2009 10:31:07 AM EST
Absolute cowit lets you confirm the zeros against each other: if the dot is off the post something has moved.
Lower 1/3 lets you have your head up more (slightly) which may be more comfortable/easy to get into/greater FOV.
It is really a preference thing as opposed to one being "better" than the other usually.
Dragonfly228  [Member]
6/4/2009 10:58:13 AM EST
if you have folding sights, especially a folding front sight, absolute co-witness is good. But with fixed sights, lower 1/3 is ideal.

I used to think absolute was the way to go, until I took a carbine combatives class. After the first day, and seeing other buddies systems, lower 1/3 with a fixed front sight tower is the way to go.
LX200  [Team Member]
6/4/2009 2:01:21 PM EST
I can't follow this....

1. 517 with built in riser gives you 1/3 ??? Or other way around
2. What does 1/3 mean.... I look in the eotech. Depending on how I hold my head, I will see the circle/dot in the bottom 1/3, and the irons will also be on target.... is that right? So if I put my head so the eotech dot appears in the center, then the irons are not on? but they have to be... with a holo sight it does not matter how you hold your head.

Damn, I am confused by this....

Any pictures/diagrams on web that show what you see ??
at4rxj  [Team Member]
6/4/2009 2:21:36 PM EST
LOL...

It's where the iron sights are in your sight picture on the optic.

Lower third puts them lower. You can still see them, but they're at the bottom. Regular co-witness puts the reticle centered on the sights.

As stated, there are positive sides to both, it just comes down to personal preference. I just wish Eotech gave you the option to have the riser or not on each model...
SuperSet72  [Member]
6/4/2009 2:26:02 PM EST
Originally Posted By LX200:
I can't follow this....

1. 517 with built in riser gives you 1/3 ??? Or other way around
2. What does 1/3 mean.... I look in the eotech. Depending on how I hold my head, I will see the circle/dot in the bottom 1/3, and the irons will also be on target.... is that right? So if I put my head so the eotech dot appears in the center, then the irons are not on? but they have to be... with a holo sight it does not matter how you hold your head.

Damn, I am confused by this....

Any pictures/diagrams on web that show what you see ??



You really need to read this thread.
http://www.ar15.com/forums/topic.html?b=3&f=18&t=402943
ToyCop  [Team Member]
6/4/2009 2:44:55 PM EST
I thought the integrated EoTech rise was so you could clear the M4 hand guards when you mount it on the forward section of the receiver. My 552 wouldn't clear without the LaRue mount.
WBK_Viper  [Member]
6/5/2009 6:23:06 PM EST
Because the Eotech is a holographic sight you can still zero the dot with your BUIS and front sight with a 1/3 cowitness. Just lower the check.

The 516 with the riser IMO is way better. The sight picture is the most important thing to me. If I want the irons I can still use them and I can still
use all three if I want. The dot is right on the tip of the front sight.
maxicon  [Team Member]
6/6/2009 2:32:36 PM EST
The integrated Eotech riser has both benefits - lower 1/3 for those who want it, and handguard clearance for those who need it far forward with fat handguards.

With an integrated riser, you've only got lower 1/3 and can't go back to absolute. Without one, you can add a riser for lower 1/3, or go with absolute co-witness if you want, so it's a trade-off there as well. The YHM riser isn't QR, and the LaRue is, but it's got that little bit of rail behind the Eotech that takes up space for people who don't use it. I'm not sure why they don't offer it without that.

Originally Posted By LX200:
1. 517 with built in riser gives you 1/3 ??? Or other way around
2. What does 1/3 mean.... I look in the eotech. Depending on how I hold my head, I will see the circle/dot in the bottom 1/3, and the irons will also be on target.... is that right? So if I put my head so the eotech dot appears in the center, then the irons are not on? but they have to be... with a holo sight it does not matter how you hold your head.


Co-witness refers to when you line up the iron sights through the optic (any non-magnified optic, not just Eotech).

When you line up the front and rear sights, the red dot will always be on top of your front sight post if both irons and optic are zeroed the same. With absolute co-witness, this happens in the center of the optic. With lower 1/3, this happens 1/3 of the way up from the bottom of the optic, rather than in the center.

For just using the optic's reticle, it doesn't need to be aligned with the iron sights - as long as you can see it and place it on your target, you're aimed correctly. The iron sights may not appear to be lined up, based on where your eye is, but they are - if you kept the rifle steady and moved your head until the dot was on top of the front sight post, the rear sights would now be aligned.


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