Another n00b question from a slow learner...

Got my 2nd build compleat.

Stag Lower, RRA HBAR 20" A4 upper, DPMS lpk, With the Eotech ECOS-C riser on an Eotech (Got the pair in a trade) and the GG&G MAD BUIS.

Now I'm co-witnessing in the lower third of the Eotech glass... If I take the riser off I'll cowitness center.

Now... my brain is thinkin' if I mount the Eotech directly, I can sell the Larue riser and buy about $100 more ammo (or more magazines, or a cool sling, or better grip, or another kewl dohickey...)

What are the pros and cons my n00bile brain may be overlooking?

It's just personal preference.

I like a lower 1/3rd cowitness. If you like a center cowitness then go with it.

I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place.

Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place.

In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be?

Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be?

Shoulda came with it, mine did.  Check into ordering a replacement directly from Eotech.



ETA, mine is mounted directly to the upper.  Nose doesn't like that when I use hot ammo though

Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be?

Still going to be tough to remove.  Its a bit more than finger tight...

I mount mine directly on the receiver flat. Cowitnesses perfectly and I can use the BUIS as it lines up in the center of the EO.

Quoted: I mount mine directly on the receiver flat. Cowitnesses perfectly and I can use the BUIS as it lines up in the center of the EO.

+1

I don't own an EOtech, so bear with me. When you mount it directly to the flat top with a fixed front sight, the dot sits between to the two flanges of the sight tower, but over the post? That's how it looks to me from the photos I've seen.

Do you have any trouble focusing on the dot? I assume that is why some people whould prefer the lower third co-witness?

Quoted: Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be? Shoulda came with it, mine did.  Check into ordering a replacement directly from Eotech. ETA, mine is mounted directly to the upper.  Nose doesn't like that when I use hot ammo though

Beware the thumbscrew.

There are plenty of experiences with EOTechs taking a dive off of rifles using the thumbscrew.

Use the hex bolt

Quoted: I don't own an EOtech, so bear with me. When you mount it directly to the flat top with a fixed front sight, the dot sits between to the two flanges of the sight tower, but over the post? That's how it looks to me from the photos I've seen. Do you have any trouble focusing on the dot? I assume that is why some people whould prefer the lower third co-witness?

The position of the reticule depends entirely on where your eye is.  

If you have the EOTech and irons sighted in properly, the reticule will be centered on the front sight post when you look through the irons, but if you move your head, the reticule moves with you.  Move your head up, it goes up.  Move your head right, it goes right, and so on.

If you mount it to the receiver and look through the iron sights, you will be looking through the center of the window with the reticule centered on the front sight post  (absolute cowitness).  If you use a riser, like the LaRue mount, and do the same thing, the reticule will still be centered on the front sight post, but you will now be looking through the lower third of the window (lower third cowitness).  

The riser allows you to use more of the window (since you can't really use the bottom without one, as it's lower than your iron sights) and when you look over the sights, you're generally looking throught the center of the window.  You can have your head a little bit higher with the riser and still see the reticule.  The advantage isn't huge, but definitely present.


ETA:  Focus is only an issue if you have astigmatism or try looking directly at the dot.  If you have good or corrected vision and just look at your target, the reticule will be in focus, although somewhat grainy because it is a hologram.

height=8

Beware the thumbscrew. There are plenty of experiences with EOTechs taking a dive off of rifles using the thumbscrew. Use the hex bolt hethis is equivalent to approximately 17 in-lb of torque" this is printed on a little bright orange piece of paper that comes packaged with the  sight. (so people might not have been tightening them enough so they added the note) it also says in bold print... NOTE: DO NOT USE ANY THREAD LOCKING ADHESIVE ON THE SCREW THREADS (such as locktite products)

Quoted: Quoted: Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be? Shoulda came with it, mine did.  Check into ordering a replacement directly from Eotech. ETA, mine is mounted directly to the upper.  Nose doesn't like that when I use hot ammo though Beware the thumbscrew. There are plenty of experiences with EOTechs taking a dive off of rifles using the thumbscrew. Use the hex bolt

I do use it, he asked about the thumb screw so I was telling him.

Quoted: Quoted: Quoted: Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be? Shoulda came with it, mine did.  Check into ordering a replacement directly from Eotech. ETA, mine is mounted directly to the upper.  Nose doesn't like that when I use hot ammo though Beware the thumbscrew. There are plenty of experiences with EOTechs taking a dive off of rifles using the thumbscrew. Use the hex bolt I do use it, he asked about the thumb screw so I was telling him.

Actually the thumbscrew is about as secure as it can be.  the units flying off are usually people that did not mount the EOTech properly.

Everyone I sold the EOTech to, I mention to them to tighten the screw to hand tight, then take a coin and give it quasrter to half turn.  and during the first time firing the gun with the EOtech, check the screw a few times and make sure the screw take a set. once you do it for the first time, you can mount and remount the unit without worries.

Quoted: Quoted: Quoted: Quoted: Quoted: Quoted: I DO like quick releases on any rifle with back up sights. The reason is that there could be a time when the optic is so badly obscured/damaged that you cannot use the BUIS with it in place. In that case... is there a thumbscrew I can replace the hexhead screw of the Eotech with, to remove it sans tools if need be? Shoulda came with it, mine did.  Check into ordering a replacement directly from Eotech. ETA, mine is mounted directly to the upper.  Nose doesn't like that when I use hot ammo though Beware the thumbscrew. There are plenty of experiences with EOTechs taking a dive off of rifles using the thumbscrew. Use the hex bolt I do use it, he asked about the thumb screw so I was telling him. Actually the thumbscrew is about as secure as it can be.  the units flying off are usually people that did not mount the EOTech properly. Everyone I sold the EOTech to, I mention to them to tighten the screw to hand tight, then take a coin and give it quasrter to half turn.  and during the first time firing the gun with the EOtech, check the screw a few times and make sure the screw take a set. once you do it for the first time, you can mount and remount the unit without worries.

+1 that is how i did it and it works for me

When I mounted my Eotechs I tightened them down with a quarter enough to bust a testicle.  After I shot the rifles to zero I had to retighten each unit two more times (about 1/8th to 1/4 turn movement) to get them rock solid.  

Thread lockers are the shit.  I use a thread locker on any scope screws.  Just use the medium or blue mixture and you can remove the treated bolts just fine.  the thread lcokers just prevent vibrations from loosening the bolts/screws.  

I'd sell the Larue and get the GG&G Accucam and then buy a couple of boxes of ammo.  

Here is my Colt Law Enforcement Carbine with a 552.A65 with GG&G Accucam mounted on a YHM EOTech riser.  Gets the EOTech right up there where the sight picture with it is far better and you dont have to smash your face onto the buttstock to get the dot in the middle of the window.  The irons (BUIS is GG&G MAD) still can be sighted through the lower part of the EOTEch window.