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6/25/2018 7:04:05 PM
Posted: 7/17/2011 10:26:09 PM EDT
What are the advantages and disadvantages of these sighting setups? I have always used absolute but i dont know why one would want to have a 1/3 cowitness view. Please educate me. Thank you.
Link Posted: 7/17/2011 11:17:59 PM EDT
Link Posted: 7/18/2011 1:44:05 AM EDT
Best explanation I've every read.
Thanks Mark!
Link Posted: 7/18/2011 1:57:55 AM EDT
That was good.
Link Posted: 7/18/2011 2:25:26 AM EDT
Thanks! Hell even this old dog learned from that explanation!
Link Posted: 7/18/2011 4:56:30 AM EDT
I definitely prefer the less cluttered sight picture of a lower 1/3 co-witness.
Link Posted: 7/18/2011 5:59:30 AM EDT
Wow, thank you very much for your knowledge and your time. The 1/3 cowitnes definitely makes more sense now.
Link Posted: 7/18/2011 7:36:17 AM EDT
Originally Posted By Semper_Firearms:
Wow, thank you very much for your knowledge and your time. The 1/3 cowitnes definitely makes more sense now.


I def suggest lowe 1/3, that said i dont have either. I have to remove my eotech to use my irons
Link Posted: 7/18/2011 1:48:15 PM EDT
Originally Posted By Willz:
Best explanation I've every read.
Thanks Mark!


+1 very good-

Sounds like I will be replacing my COMP M4s LaRue mount for the proper 1/3 LaRue mount very soon.

Thanks

Joe
Link Posted: 7/18/2011 5:03:11 PM EDT
Link Posted: 7/18/2011 5:28:18 PM EDT
I thought that was a great write up and made a lot of great points about the lower 1/3 cowitness.

Despite that, I personally prefer an absolute co-witness, so I thought I would share my reasoning.

I learned on iron sights and shoot my rifle nose-to-charging-handle. Its the way I am most comfortable, but it puts my eye very low over the top of the rifle...but perfectly in-line for the iron sights.
When I started using an Aimpoint, I didn't want to have to change my technique for holding the gun. That meant an absolute co-witness.
Another difference is that I use fold down BUIS. Aimpoints, Eotechs and ACOGs are EXTREMELY reliable. I use an Aimpoint. The chance of me having to go to my irons is slim, so I keep them out of the way. If I need them, I will have to flip them up and yes, it will take time. But I can hopefully get to cover or fight my way there even with broken sights, just point shooting, so that I have 3 seconds to flip them up. A lot of people like the sights that require you to press a button to flip them up, but I, personally, prefer either YHMs, which stay down just fine, but are not locked and can easily be flipped up, or Magpuls which only take a quick smack to get upright.
Lastly, even with a lower 1/3, I don't like the clutter in the bottom 1/3 of my sight.

That's the basis of my reasoning, but as with many things when it comes to this 'game,' I recommend you do what works best for you. The only wrong way is the way that gets you killed.
Link Posted: 7/20/2011 6:46:25 AM EDT
great write up from larue tactical
Link Posted: 7/20/2011 8:03:21 AM EDT
Originally Posted By Bub0214:
great write up from larue tactical


+1. I knew that already, but have never seen a clearer visual depiction on the web. Very well done and thanks to LaRue for posting. Might be why I have a dozen "beverage entry" tools even after giving a half dozen away.

Link Posted: 7/20/2011 3:39:38 PM EDT
Very thorough article Mark, and completely applicable to M-series Aimpoints. However, with the smaller lens of the micros, the geometry of the LT-660 "lower 1/3 co-wit" is mathematically lower 1/4, a horse of a slightly different color.
Link Posted: 7/20/2011 4:36:03 PM EDT
Thanks for that, I was wondering myself which would be best for me.
Link Posted: 7/20/2011 5:32:45 PM EDT
Link Posted: 7/20/2011 7:46:44 PM EDT
Originally Posted By mfingar:
Originally Posted By murderman:
Very thorough article Mark, and completely applicable to M-series Aimpoints. However, with the smaller lens of the micros, the geometry of the LT-660 "lower 1/3 co-wit" is mathematically lower 1/4, a horse of a slightly different color.


http://i2.photobucket.com/albums/y44/mfingar/LaRue_Tactical/LOWER1-3.jpg

LaRue cowitness charts


Thank you for the excellent chart Mark, it clearly illustrates exactly what I was pointing out. Using a 660 puts the co-wit 1/4th of the way from the bottom of the lens to the top.

Link Posted: 7/20/2011 8:59:19 PM EDT
[Last Edit: 7/20/2011 9:20:48 PM EDT by mfingar]
Link Posted: 7/20/2011 9:37:53 PM EDT
I've used both and greatly prefer lower 1/3. I use fixed sights because if my optic fails in a fight I don't want to be flipping up sights. Lower third just reduces clutter for a much clearer sight picture while still employing fixed sights.
Link Posted: 7/20/2011 11:45:57 PM EDT
I never like the idea of the EOtech's on risers until I tried one (built into my new 553). It's great, you can leave the sites up (or used fixed), and they never interfere with your sight picture. I like it so much that I bought a riser for my old 512.
Link Posted: 7/21/2011 3:59:18 AM EDT
Originally Posted By mfingar:
I think you may be confused.

When describing "Lower 1/3", the viewing area down the tube has 4 vertical segments and 3 imaginary lines that seperate those segments. By saying "lower-1/3", it is meant that the irons intersect the lowest of those three lines when centering the red dot's reticle in the tube.

http://i2.photobucket.com/albums/y44/mfingar/LaRue_Tactical/LOWER1-31copy.jpg

The size of the tube doesn't matter.

All that being said, we do our best to come as close to what is described...in other words, our "lower 1/3" may be a hair off...but is in the general area. The principal idea is to get the irons out of the way, but still make them usable.


ETA:
You may be thinking of this type of area dispersion when picturing "lower 1/3". Not really how we do it. It's too ambiguous.
http://i2.photobucket.com/albums/y44/mfingar/LaRue_Tactical/LOWER1-32.jpg


Mark, with all due respect, I am not at all confused. May I suggest that we are just going to have to agree to disagree on the semantics, as your great illustrations again clearly indicate that LT's definition of "lower 1/3" places the dot mathematically 1/4th of the linear distance from the bottom of the lens to the top when co-witnessing standard height iron sights. It is what it is.

Take care, J
Link Posted: 7/21/2011 7:03:10 AM EDT
[Last Edit: 7/21/2011 7:03:58 AM EDT by LaRue_Tactical]
Link Posted: 7/21/2011 10:23:09 AM EDT
Good afternoon Mark (L.), long time no hear. Hope that all is well for you.
Link Posted: 7/21/2011 11:22:14 AM EDT
Thanks for the great write-up.
Link Posted: 7/21/2011 12:18:45 PM EDT
I learned quite a bit from this thread, but it just makes me want my aimpoint with my lower 1/3 mount even more, so I can physically relate it to what I am reading.

Hopefully tommorow!
Link Posted: 8/2/2011 9:14:23 AM EDT
This is pure gold!

So what if you are not going to have fixed or BUIS at all on a AR? Is there then any advantage to a higher mount?

I ask because I am going to build a Competition only type AR and won't have any irons on it, just a RDS.
Link Posted: 8/2/2011 9:55:48 AM EDT
Originally Posted By BillyDoubleU:
This is pure gold!

So what if you are not going to have fixed or BUIS at all on a AR? Is there then any advantage to a higher mount?

I ask because I am going to build a Competition only type AR and won't have any irons on it, just a RDS.


I would say in that case its whatever works for you to put rounds on target. Whichever is more comfortable.
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