"FINAL" Word on Optics Picatinny Rail Placement?

JBS

Leatherneck
Verified Military
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I am looking for resources, opinions, guidance, and instruction on ideal placement of optics on rails. Specifically I am referring to detailed data on proper eye relief, elevation from the plane of the barrel, and with most of the emphasis on maximizing accuracy.

For example, I cannot find conclusive data on the proper placement of the EOTech XPS-2/3 series on a rail. I have read all of the following, just on the "proper" placement of EOTechs:
  • Wherever it is most comfortable for you personally
  • As far forward as possible, for max eye relief
  • As far back as possible for weight considerations; the reticle remains the same size at all times anyway
  • Anywhere but over the barrel to avoid excess heat or loss of zero on free float guards/rail setups
  • Excess heat doesn't matter with the EOTech because it's a battle-ready device; put it anywhere- including over the barrel- so long as it won't interfere with BUIS
I read from an EOTech bullet point summary that the reticle will always remain 60MOA, no matter how close or far away it is from the eye, and I can see that happen when I hold it over a target with known dimensions; this seems to lend credence to the notion that eye relief in the device itself is a non-issue, since the reticle always will stay the same size relative to the target. Still, this does NOTaddress the fact the reticle takes up a larger portion of the sight itself reducing usable viewing area, and also whether greater accuracy at 200+ meters will be obtained by optics placement in general.

And I know I went on about the EOTech, but I'm also interested in learning the ideal placement for other optics if there are resources for that. It's my belief that little details like this- rarely expertly addressed- can take a very good, otherwise highly disciplined shooter and make him a 1%'er type shooter.

Or is there even a "right" answer?


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There is no eye relief for the EoTech. I like mine far enough forward that my BUIS does not affect the operation of the optic controls (buttons), but on the upper flat top. Normally flush with the front edge of the upper (not the forward rail but the flat-top rail). The best answer would be where you get the best performance times (use a shot timer) on mounting the gun and firing from a low ready position. If you find yourself fishing around to find the reticle, move the optic until it’s automatic when you mount the gun (get proper cheek weld).

As for hard copy data, no I do not have any. You miht contact EoTech directly.
 
If it's something with eye relief, I'll just scoot it around while in a comfortable firing position until it's in the "right spot". Then try mounting the rifle in other positions to ensure where I have it hand tight still works for everything else.

No eye relief? Where it works, I can use the flipups, and access all controls. There's an argument about sight radius with positioning, IE movement with a reflex further from your eye will be more blatant as a change of POA, but I personally like mounting my optics flush with the front of the rail for a railed upper... monolithic? About the same, between ejection port and chamber thereabouts.
 
I don't have anything but anecdotal observations. I run an Eotech HWS and magnifier on my duty rifle, and the HWS is only as far forward as it needs to be to allow the magnifier to sit on the rail. The rear edge of the magnifier is about even with my BUIS (I'll post a picture tomorrow; it'll make more sense that way). Without a magnifier I prefer the Eotech just forward of the rear BUIS. For me personally, I like the HWS closer to my eye but that may just be personal preference. I haven't noticed any significant difference in accuracy or speed with the Eotech a bit further from my eye to accomodate the magnifier.
 
This works for me; YMMV.

View attachment 7596
I actually run mine like this now, although previously I had my XPS almost all the way even with the upper, and had run it like that for a long time. I like both ways- but if I am not running some sort of flip down 3x, I am partial to pushing the optic a little further on the rail. Just a personal preference.
 
If you are running an EoTech in conjunction with the EoTech Magnifier you tend to have to run the setup as far back as possible as the eye relief on the magnifier is horrid.

With any magnified optic you are going to want the optic to sit wherever it is most comfortable to acquire proper eye relief.
 
My dream AR rifle is an LWRC M6 IC with a 16" barrel. It doesn't exist so I guess I'd go with an M6A2 SPR.

We're both drooling over the same gun. The M6 IC is awesome. But like you say, it's the ballistic equivalent of a unicorn until LWRC can start producing them in any number. The first run of 500 were spoken for before they were made, I heard.
 
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