Explanation of Co-Witness

[akula88]

There is no "better".

Lower 1/3 or so-called "SOCOM" co-witness gives a bit better field of view, some might say is less "cluttered."

But many run absolute co-witness just fine, and some prefer it because it shoulders the same/uses same cheekweld as irons.

This is one of those preference areas.

I now understood the FOV advantage, but I need clarifications on Point of Impact on 1/3 Co-Witness when zeroing the Red-Dot sight.

At 1/3 Co-Wit, practical wisdom says that (except at zeroed distance [example-50yards]); the point of impact between red dot and iron sight is slightly different. Further at distance beyond the 50-yards, accepted and 'published' ballistic trajectory would be off for the red dot sights, since it sits HIGHER compared with the iron sight plane. (Axis to bore ratio)

Is this concern valid or just purely hot gas??

I sat back and thought about this over the weekend over many, many pints of Guinness and using the term "Co-Zero", if your BUIS or Sight already sit in thee bottom 1/3 of your Optic / Red Dot, and your BZO your Optic /Red Dot @ 25m, and then adjust your Sights to it, your will not have a correct 300m BZO. Or even the other way around.

Lets just say that you sight in your Optic / Red Dot @ 25m and then adjust your Irons to them. Well then look at the setting on your elevation, it will be way blown out due to the fact that you (from the start with your lower 1/3 co-witness) have a gross adjustment of coming up at .25" or more. Then after your Rear is at the correct level, bringing your front sight post up to Co-Zero would be almost to the point of your Front Sight Post and Detent coming out or damn close to it.

IF your sights are on the same level with a Co-Axis with the plan of each being the same plan, it would be close or if not perfect for the idea of Co-Zero to work.

And going back to another question that was brought up earlier (sorry for hi-jacking my own thread). There is DIFFERENT POA/POI for different Optics / Red Dots with many variables in place, ammo types, optics, bbl lengths, etc. Example: Say you sight a EOTech in @ 25m (and the offset is 1.25 low) and your think that your POA/POI in Center mass of the Black Dot or Circle and your zero it to that. Then push your 25m BZO to 300m and see what happens. IF you were at center mass on that @ 300m your will be aprox. 15” High, and that is in perfect conditions taking out all accountable errors, IE MOA of ammo and the aprox 1 MOA for shooter added to the MOA of the gun. In all reality your could be pushing to a extreme of almost 30” off your center mass BZO @ 25m. Hope that makes sense !
B

My intention would be to shoot the red dot to as far as 200yards or slightly farther.

Please post your opinions...

[Cameron]

I have two carbines set up with an EOtech:
one with the fixed front sight has a bottom 1/3 as I use a larue riser to keep the front sight out of the main portion of the EOTech window, the other has a flip up front so I don't need a riser and this gives a perfect co-witness in that the circle and the dot align exactly with the BUIS.
Neither of then cause a need to change POI/POA for the differing set ups as the difference is only a change in optic over bore of about 5/8" for the EoTech riser vs. EoTech sans riser... So I Zero at 50 yards with dots and irons all impacting the same.

[Outlander Systems]

Here's my equation, which may or may not resonate with you:

Backup iron sights:

Fixed - Go with a lower 1/3rd, you'll appreciate it.

Folding - Doesn't really make a difference, but lower 1/3rd can often be a bit taller than I'm naturally inclined to shoulder the weapon with. Absolute cowitness in this situation.

It's a matter of personal preference. I seem to work better with an absolute cowitness, but that's just me.

[TheDarkOne]

I hate to keep beating this horse, but I would like a little more opinion as to which height optic people prefer and why.

I just got my lower 1/3 SOCOM riser from ADM, but am having second thoughts. What I hate is the new cheek weld, or "chin weld", required to shoot it. To me, keeping that cheek weld consistent aids to repeatability and accuracy. When you cheek that weapon system, it should feel the same every time. Thoughts?

Btw, I am running flip up irons and have them folded down.

[C4IGrant]

I hate to keep beating this horse, but I would like a little more opinion as to which height optic people prefer and why.

I just got my lower 1/3 SOCOM riser from ADM, but am having second thoughts. What I hate is the new cheek weld, or "chin weld", required to shoot it. To me, keeping that cheek weld consistent aids to repeatability and accuracy. When you cheek that weapon system, it should feel the same every time. Thoughts?

Btw, I am running flip up irons and have them folded down.

I only run a lower 1/3. Why? Because I want as little of my FOV blocked as possible.

The more you head is "up" the better situational awareness you have.

Cheek weld does not matter when using a RDS (FYI). You can be upside down and hit your target as long as the dot is on it.

Sights should be up and ready to go. Too many times we see guys optics fail in training classes and then they are screwed as they have their sights down.


C4

[rob_s]

I run lower 1/3 mounts entirely. I also prefer fixed front and rear irons, or irons flipped up if they have the capability. I run my guns with my nose on the charging handle and have no trouble finding the dot on either 30mm or micro Aimpoints.

When I have been forced to use an absolute cowitness mount I have felt like I was mashing my face into the stock, and I absolutely want at least a flip down rear sight (the front effectively ghosts away).

You might try a Knight's micro mount as IIRC it comes with two risers to give you either absolute or lower 1/3.

[TheDarkOne]

I only run a lower 1/3. Why? Because I want as little of my FOV blocked as possible.

The more you head is "up" the better situational awareness you have.

Cheek weld does not matter when using a RDS (FYI). You can be upside down and hit your target as long as the dot is on it.

Sights should be up and ready to go. Too many times we see guys optics fail in training classes and then they are screwed as they have their sights down.
C4

I can see if you are running the irons up that lower 1/3 is optimal. (Btw, I bought my optic and riser from you, thanks for the good price ). Realistically though, how often are these red dots going down? In the rare case that they do, I wouldn't say the shooter is screwed. You can still shoot through the tube, and those irons take less that 1 second to deploy.

I know cheek weld doesn't matter with aiming with and RDS, the bullet goes where the dot is, but I think it does matter with stability. Controlling recoil, shooting rapidly, transitioning between targets, etc. I think the more consistent and tighter things are, the better you shoot.

[TheDarkOne]

I run lower 1/3 mounts entirely. I also prefer fixed front and rear irons, or irons flipped up if they have the capability. I run my guns with my nose on the charging handle and have no trouble finding the dot on either 30mm or micro Aimpoints.

When I have been forced to use an absolute cowitness mount I have felt like I was mashing my face into the stock, and I absolutely want at least a flip down rear sight (the front effectively ghosts away).

You might try a Knight's micro mount as IIRC it comes with two risers to give you either absolute or lower 1/3.

That smashed cheek feeling is what I like, or at least what I am used to. It just feels more stable to me. Plus it is the same weld as with irons.

I am using an ADM Mount which is modular as well, so I can change out risers if I want to. I am just trying to figure out which way to go before I spend the money. The new riser is only about $25 but I don't want to spend more unless I am sure.

[C4IGrant]

I can see if you are running the irons up that lower 1/3 is optimal. (Btw, I bought my optic and riser from you, thanks for the good price ). Realistically though, how often are these red dots going down? In the rare case that they do, I wouldn't say the shooter is screwed. You can still shoot through the tube, and those irons take less that 1 second to deploy.

I know cheek weld doesn't matter with aiming with and RDS, the bullet goes where the dot is, but I think it does matter with stability. Controlling recoil, shooting rapidly, transitioning between targets, etc. I think the more consistent and tighter things are, the better you shoot.

Optics are man devices and fail all the time.


Using the optics tube to shoot only works ok at best. When only hits count, why risk it??? How much training have you done with the tube only? How far was the target? How big was the target?

It takes longer than 1 second to deploy your optic and generally what happens is the shooter sits there for 10 seconds trying to figure out where their dot went.

No on stability, controlling recoil, shooting fast or engaging multiple targets. What DOES help with all of this is recoil management, muzzle flip control and trigger discipline. The bulk of these things are controlled by your weight balance, where your arms/hands are on the weapon and how you are applying force.


C4

[Outlander Systems]

I can see if you are running the irons up that lower 1/3 is optimal...

A wise man once said, and I'm paraphrasing, "There's a reason they're called back UP iron sights"...

Just sayin'.