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Posted: 10/30/2009 5:31:09 PM EST
The Chief wants me to pick an EOTech that will be mounted on a Smith and Wesson M&P15X and also usable on a Colt 6920 and Rock River 6920 clone. Good or bad, he's not interested in an Aimpoint or Trijicon.

Man, there sure are a lot of different EOTechs!

Here's what we're looking for:

Lower 1/3 co-witness with factory front sight (rear sight is a Troy folder). Unless we get a separate riser, I think that means we need the 7mm raised base, right?

Lever attachments instead of the cross-bolt. The levers should work ok with the 3 brands of rails we have, right?
Any problems with the lever system?

The only two models that have these features seem to be the 555.A65 list $669, and the A553.A65 list $699, I can't figure out what is different between them except for the batteries.

Comments or suggestions? Remember, it's gotta be an EOTech...
Link Posted: 10/30/2009 5:45:25 PM EST
The lever requirement restricts you to a very few models like the ones mentioned.
Can you have him reconsider the lever since the bolt attachment will open you up to the XPS or the 516/517 models?
Link Posted: 10/30/2009 5:45:58 PM EST
Grab him a 512 or 552 with the LaRue QR mount. This will give him a lower 3rd co-witness, and a QR mount. Its also arguably the "most" reliable of the EOTech, as in: least reported problems.

The GG&G will work in the 552/512 and 551/511, but not in any of the other models. It doesn't raise it at all.

The 553 uses ARMS mounts, and unless he plans to ONLY use them as "emergency off" levers then they WILL wear out eventually. Might be 50 cycles, might be 100, but they always do wear out, and if they do they cant be tightened without using shims and other mickey mouse fixes for a poor design.
Link Posted: 10/30/2009 5:57:29 PM EST
XPS with Larue mount.
Link Posted: 10/30/2009 6:45:34 PM EST

...
The 553 uses ARMS mounts, and unless he plans to ONLY use them as "emergency off" levers then they WILL wear out eventually. Might be 50 cycles, might be 100, but they always do wear out, and if they do they cant be tightened without using shims and other mickey mouse fixes for a poor design.

The plan is to use the ARMS levers only if the EOTech fails (insert humor here) or some other servicing issue. I like to think they would last a long time in that use, but I don't really know. Shims to correct wear would be ok if we can install them ourselves, I wonder how they convinced the government that this is an acceptable system. Maybe it's been improved?

The big reason for the levers is so an officer could easily remove the EOTech in a hurry, if it takes a dump on him; to use the irons more easily. If we have the cross-bolt mount, then it needs LocTite and I don't want an officer looking for tools to loosen the bolt while someone is shooting at him.

This reminds me of what would happen if you left three bowling balls overnight in a police station:
By the next morning,
One would be broken
One would be missing
One would be pregnant.



Link Posted: 10/30/2009 7:12:40 PM EST
[Last Edit: 10/30/2009 7:15:03 PM EST by F22_RaptoR]
Originally Posted By GJim:

...
The 553 uses ARMS mounts, and unless he plans to ONLY use them as "emergency off" levers then they WILL wear out eventually. Might be 50 cycles, might be 100, but they always do wear out, and if they do they cant be tightened without using shims and other mickey mouse fixes for a poor design.

The plan is to use the ARMS levers only if the EOTech fails (insert humor here) or some other servicing issue. I like to think they would last a long time in that use, but I don't really know. Shims to correct wear would be ok if we can install them ourselves, I wonder how they convinced the government that this is an acceptable system. Maybe it's been improved?

The big reason for the levers is so an officer could easily remove the EOTech in a hurry, if it takes a dump on him; to use the irons more easily. If we have the cross-bolt mount, then it needs LocTite and I don't want an officer looking for tools to loosen the bolt while someone is shooting at him.

This reminds me of what would happen if you left three bowling balls overnight in a police station:
By the next morning,
One would be broken
One would be missing
One would be pregnant.





The point of have a co-witness (lower 3rd or absolute) is so you can use Iron sights through the optic without having to remove it.

as for "shims", its a thing that you would have to make and engineer yourself. Some people have taken thin sheet metal and wedged it between the clamp bar and the lever cam to "thicken" it up a bit. This is what I meant by using shims, so if they ever open it the shim is going to fall out etc.... not a very good idea.

The 553 is pretty much a 552 with raised height. You can get pretty much the same thing but with much higher quality of the locking system, by getting a 552 or 512 with the LaRue mount.

You can get the 512 with LaRue mount from LaRue for $459, or if NVG is required, you can get the 552 with LaRue mount from LaRue for $574. They have package deals on their website.

From Bravo Company, the 553 is $639.00, so your saving about 60 bucks getting a much better mounting system, and more common batteries (AA instead of CR123. Although the CR123's may be what you use in weapon lights)


You can loc-tight the snot out of the cross bold onto the LaRue rail, then never worry about it again. The throw lever is adjustable with a wrench, so you don't have to worry about the officers bumbling with the locking system either. Just open it or close it.
Link Posted: 10/31/2009 8:40:22 AM EST
[Last Edit: 10/31/2009 8:53:05 AM EST by GJim]
Thanks for the comments.
I've got a LaRue mount (with a Leupold 1.5 x 5) on my personal 6920, the quality is outstanding.
The LaRue/EOTech combo is starting to look good.

I'm undecided about the batteries; AA are cheap and plentiful, lithium AA are nearly as good as 123 but expensive.
We'll probably end up with a light that uses 123's, so commonality would be nice.

How well does it work to use a flip-up rear sight (Troy/LaRue) with lower 1/3 co-witness, without removing the EOTech? Leaving the EOTech in place worked ok for me when testing a gun that had center co-witness, but I never tried one with lower 1/3.
Link Posted: 10/31/2009 11:18:31 AM EST
512 on a LaRue LT-110 FTW.
Link Posted: 10/31/2009 11:28:20 AM EST

Originally Posted By F22_RaptoR:
Grab him a 512 or 552 with the LaRue QR mount. This will give him a lower 3rd co-witness, and a QR mount. Its also arguably the "most" reliable of the EOTech, as in: least reported problems.

The GG&G will work in the 552/512 and 551/511, but not in any of the other models. It doesn't raise it at all.

The 553 uses ARMS mounts, and unless he plans to ONLY use them as "emergency off" levers then they WILL wear out eventually. Might be 50 cycles, might be 100, but they always do wear out, and if they do they cant be tightened without using shims and other mickey mouse fixes for a poor design.

+1
Link Posted: 10/31/2009 12:35:54 PM EST
Originally Posted By GJim:
Thanks for the comments.
I've got a LaRue mount (with a Leupold 1.5 x 5) on my personal 6920, the quality is outstanding.
The LaRue/EOTech combo is starting to look good.

I'm undecided about the batteries; AA are cheap and plentiful, lithium AA are nearly as good as 123 but expensive.
We'll probably end up with a light that uses 123's, so commonality would be nice.

How well does it work to use a flip-up rear sight (Troy/LaRue) with lower 1/3 co-witness, without removing the EOTech? Leaving the EOTech in place worked ok for me when testing a gun that had center co-witness, but I never tried one with lower 1/3.


Lower 3rd co-witness works quite well, especially if you're using fixed iron sights (AKA non folding), since you get more room to view the retical in, without your iron sights getting in the way.
Link Posted: 10/31/2009 12:50:17 PM EST
I worded my question poorly. What I was trying to ask is:
The rear sight would normally be folded down, are there any issues with flipping it up and using it (and the fixed front sight) without removing the EOTech, when we have lower 1/3 witness?
Link Posted: 11/2/2009 1:52:55 AM EST
Originally Posted By GJim:
I worded my question poorly. What I was trying to ask is:
The rear sight would normally be folded down, are there any issues with flipping it up and using it (and the fixed front sight) without removing the EOTech, when we have lower 1/3 witness?


No problem at all. You can use it perfectly with the rear sight flipped up and keep it like that. That's what's great about 1/3 co-witness. The sight sits so low in the view that it doesn't clutter your sight picture.

I use a fixed FSB and Larue Fixed BUIS and the 1/3 works perfectly for me. I had a 552 with a Larue riser/mount, but sold the 552 because I wanted to switch to something that used CR123A batteries (I prefer the same batteries for ALL of my devices). So now I am waiting to get home and play with the new XPS 3-2 I bought.

IMO, Absolute co-witness is best when your using flip-up front and rear BUIS and you keep them folded down.

Nathan

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