My wife got me a Colt LE6920 for Christmas and my son got me a Eotech XPS2 to go with it. The LE6920 has a A2 type front sight and gas block combo and the rear sight is in a removable handle. I have shot the gun with the original sights and have zeroed it for 100 yards as that is within the range where it will mostly be used. Now I want to setup the Eotech XPS2 and zero it for 100 yards. I will be removing the handle and mounting the sight directly on the upper rail my question is, Is there such a thing as being to close to the Eotech with your eye or is there a range for eye relief that practice has proven to be best? Looking at pictures you see them mount in various positions. I have mounted it on the gun in several positions and with it all the way back as far as I can mount it and still use the charging handle seems to give the best both eyes opened picture. Just trying to avoid a long ammo waisting learning curve if I can.

It is up to you. I suggest getting a rear sight and put that on. I run my aimpoint towards the front.

I push mine towards the front of the receiver.  Enough to not hinder the button controls on the rear of the sight, especially when used with gloves worn.

I can understand your concern for being too close.  
If you mount it too close you will lose one of the biggest benefits of this type of sight: peripheral vision.

It's not magnified, so it's basically left to your preference.

Absolutely.

Most are run at the forward edge of the upper receiver.

Sorry to hijack but, can it be too far forward? If I wanted to mount one on the top rail of my forearm would that work?

It would work. I have seen quite a few mounted like that. The only thing you are going to run into moving the optic forward is throwing off the balance of the rifle.

Congrats!!   Nice Stuff!!   I use EOTech optics on my M-4's and love them.  

The only reason to mount the EOTech as far forward as shown in these photos is if you have a fixed carry handle.  

The farther away the optic, the more distractions around the optic.  It also reduces your field of view, looking through the optic.  

These circumstamces are far from ideal.   EOTech has a photo gallery on their website.  Talke a look at how the optics are mounted in those photos.  

Mount the Eotech as far fwd on the upper receiver as possible. It is an optic meant to be used with both eyes open.

You might also consider buying the EXPS as it has the built in riser for lower 1/3 co-witness. You should also add a BUIS in case the Eotech fails.

Pics of my 6920

I place mine back a notch from the most forward upper receiver location and since it is the "E"XPS model, I can run a magnifier plus rear BUIS without blocking my optic buttons.

As every body else has said there is no problem mounting the EoTech as far forward as you like. I mount mine just forward of the chamber. I feel at that point it give me the best peripheral  vision without causing the rifle to fell somewhat  front heavy.

There are downsides with potential handguard flex if you mounting the optic forward onto the handguard.  

Red dots don't really have an eye relief like magnified optics.  Its more of an infinite tube with no too close or too far.

If you run a front sight, then mounting the optic all the way to the rear is fine, and if you don't run a front sight, then I'd run it up against the front of the upper to help you align the gun with the target slightly quicker, but its a very minor difference.  Practice more, worry less.

Thanks for the pictures! Thats exactly what I wanted to know.

DING DING DING!  With the Biden Aiming Concept I like my holographics forward more for peripheral vision.