When using a co-witness red dot, do you ignore the front sight?

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redneck

redneck

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I got my first red dot today. I bought on of the Vortex Sparc II sights that Brownells had on sale for $125. Overall the sight seems nicely finished, it came with extra screws, 2 mounts and a spacer, and 2 batteries. It mounted easily and seems solid and I didn't have too much trouble getting it on target. The adjustment clicks are pretty mushy but still usable. 1 MOA clicks are hard to get used to when you are used to 1/4 MOA but I got it on paper.

The dot itself sucks. Its pretty much a snowflake. Maybe an angry spider. It also seems much bigger than 2 MOA but I didn't think about the fact I had it on the highest setting during the little bit of shooting I did today. I have it on an M4 and don't really care for it for target use but I think for defensive purposes it will work out just fine.

My question is on how to properly use the co-witness set up. I thought that red dots were supposed to be basically parallax free, but I noticed that depending on my cheek weld the front sight moves in relation to the red dot quite a bit. I understand that if the battery were dead and I had to use it as an iron sight that I would have to keep the front sight centered in the optic, but if I am using the actual red dot, do I ignore the front sight? Or do I need to line the dot/spider/snowflake up with the front sight each time?
 
My Aimpoint Comp M3 is a red squid.

Ignore the front sight. Dot only, or irons only, pick one. Generally with Aimpoints I use flip down sights. With Eotechs, I might prefer more permanent cowitness.

You'll need to flip up a rear sight for your irons to work. Make sure to zero your irons without turning the dot on. The technique of aligning the irons to the dot, sucks.
 
Also, dots may appear different based on your eyes. For example, most my red dots are Aimpoints...but the dot is misshapen, due to my astigmatism, not the glass...good dots and bad eyes, bad dots and good eyes, etc....
 
If you’re seeing a snowflake or a spider, congrats! You have astigmatism!

Now, flip up your rear sight (you do have a rear sight, right?), set the aperture to the smallest setting, and look down range through the rear sight and the red dot. Your red dot should change from a misshapen blob into a nice, fine, 2 moa dot!

I have astigmatism too and use that trick on my defensive AR. I have my sights set up as an absolute cowitness and have both my front and rear sights flipped up. The rear sight is up so I can use the trick referenced above, and I just look through the front sight and ignore it. You could flip it down as it’s not needed when using a dot. I leave mine up so that on the off chance something happens to the dot (it’s an Aimpoint, but things happen), I already have my irons ready to go.
 
Thanks guys, it sounds like maybe I should try to install the spacer and go for 1/3 co-witness, and then also buy a flip up rear sight at some point. With the current set up the dot lands right on the tip of the front iron sight and that makes it somewhat hard to ignore although I am sure with practice it would be fine. I have it on a basic windham weaponry M4 that had a detachable carry handle with the rear sight in it and an A2 style front sight (I hope I got that part right, I am not an AR guru). I took the carry handle off to mount the Sparc so at the moment I have no rear iron sight, and I have a front sight that can't be folded or moved out of the way.
 
Ignore the front sight when using the RDS. I focus on the dot, the iron sights "disappear".

As the other's said, use the RDS or use the irons, don't try to use both. It's not needed and you'll slow yourself down dramatically. Kinda like watching someone try to align a laser with their sights. Coolest aspect of the RDS is the reduced parallax, which decreases the need for a proper cheek weld when shooting from awkward positions. That's part of the reason why the dot moves in relation to the front sight.

My carbines set up for defensive use have fixed front sights, IF push comes to shove I can use the RDS tube like a giant ghost ring and still make decent hits out to 50yds. IF things go wrong, it's one less thing to flip up. I usually like a lower 1/3rd, but the last setup I did was an absolute and the irons still dot bother me when focusing on the dot.

Try turning the brightness down when you need precision. I dial up when shooting fast. I normally sight in my irons, then co-witness the RDS to the irons, then shoot to confirm and adjust. My RDS has always been a click or two off from my irons.
 
Zerodefect said:
My Aimpoint Comp M3 is a red squid.

Ignore the front sight. Dot only, or irons only, pick one. Generally with Aimpoints I use flip down sights. With Eotechs, I might prefer more permanent cowitness.

You'll need to flip up a rear sight for your irons to work. Make sure to zero your irons without turning the dot on. The technique of aligning the irons to the dot, sucks.
Click to expand...

Same here. With an Aimpoint or similar optic, I prefer to use flip ups or a lower 1/3. I find the front sight distracting. With an Eotech, or any other device that is harder to find the reticle in sometimes, the front sight is a good reference point to get you on target.
 
Its possible I have an astigmatism as well but I generally do well on eye exams and stuff. I see the spider very clearly in the sparc II if that means anything :D
Long term I think I will end up putting a 1-4x scope on the M4 and putting the red dot on something else, maybe my buckmark camper. I don't think I'll ever be very happy with the 2 MOA dot at distance and a low power variable would let me shoot at longer ranges when necessary. This set up will work until I have the money for that, just have to work some of the bugs out.
 
Chuck R. said:
Ignore the front sight when using the RDS. I focus on the dot, the iron sights "disappear".

As the other's said, use the RDS or use the irons, don't try to use both. It's not needed and you'll slow yourself down dramatically. Kinda like watching someone try to align a laser with their sights. Coolest aspect of the RDS is the reduced parallax, which decreases the need for a proper cheek weld when shooting from awkward positions. That's part of the reason why the dot moves in relation to the front sight.

My carbines set up for defensive use have fixed front sights, IF push comes to shove I can use the RDS tube like a giant ghost ring and still make decent hits out to 50yds. IF things go wrong, it's one less thing to flip up. I usually like a lower 1/3rd, but the last setup I did was an absolute and the irons still dot bother me when focusing on the dot.

Try turning the brightness down when you need precision. I dial up when shooting fast. I normally sight in my irons, then co-witness the RDS to the irons, then shoot to confirm and adjust. My RDS has always been a click or two off from my irons.
Click to expand...
^this, especially the part about a defensive rifle and using the RDS as a giant ghost ring.

but I’ll also add, sight in your irons and optic separately. Ideally your red dot should be close to your front sight when getting a proper sight picture using rear sight, optic and front sight. As stated when shooting use one or the other not both as this will slow you down. This is really only used as a test/in relation sort of situation after sight ins.
EDIT: this is when using an absolute co-witness.

**ALSO, try NOT to focus on the front sight or the dot itself, that could be why your dot does not look crisp, focus on the target and where you want to be aiming and place you’re dot over that keeping your target in focus.

I’ve noticed with my trijicon MRO if I focus on the dot it looks like a cluster of 3 or so dots. When I focus on the target it looks much more crips. This also has to due with using the proper brightness setting for the lighting conditions.
 
Last edited:
you should be focusing on the target not the sights.

The dot will float on the target. the front sight should disapear.

i sometimes shoot my aimpoint pro with the front dust cap closed.
 
My eyes can no longer deal with open sights so putting on a red dot is kind of like giving up.
Putting on a red dot becomes a total commitment and I only put on good ones.
I've either ignored or knocked off the front sight when putting on a red dot.
 
Thanks everybody, this is all good advice. Have to see if I can't make things work better on my next range day.
 
DukeConnor gets it. When using irons, focus on the front sight. When using an RDS, focus on the target. Lower 1/3 or absolute cowitness is user preference.
 
Where do you have the sight mounted on the M4? It should be as far out in the rail as possible.
 
TonyAngel said:
Where do you have the sight mounted on the M4? It should be as far out in the rail as possible.
Click to expand...

Its right over the dust cover, I have 3 notches left in the rail moving forward. Maybe I will try and move it next time I have time to mess with zeroing it again.
 
Honestly I think it's personal preference. How I've mounted mine, I use cantilevers to position as far FWD while still on the receiver:



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I find it helps your FOV "around" the optic as it obstructs less. FOV through the optic is decreased some, but I find it not an issue at the distance I use a RDS for.
 
redneck said:
Its right over the dust cover, I have 3 notches left in the rail moving forward. Maybe I will try and move it next time I have time to mess with zeroing it again.
Click to expand...

Yes, the farther forward it is, the smaller the dot will appear to be. You'll also be pointing more with the rifle than you will with the tube of the scope. Years and years ago, me and a gunsmith buddy of mine did an experiment. We found the smallest red dot that we could and we soldered a section of pic rail the end of the barrel of a shotgun and then took it out to shoot skeet. Wow. Did it work?!
 
I will give that a try next chance I get. I am tall with knuckle dragging long arms, have a 31" draw on a compound bow if that tells you anything and honestly the LOP on my M4 feels awfully short, so I suppose that would compound the problem of having the sight too far back as its also easy for me to creep up the stock closer to it. .
 
if you see the parallax effect, don't worry, it your eye position, the dot should still be good. The effect should disappear if you look through the rear sight.
 
Your RDS is parallax free. That means when you move your head and the RD moves, it will still impact at the RD. Not so if your sight is not parallax free. This way you don't need to worry about having a perfect cheek weld so long as you can see the RD.

1/3 co-witness is nice so you have more room above the frost site. As mentioned above, if your iron sights are sighted in, just place the RD on the front post when the iron sights are aligned. But when you shoot the RDS, the RD will normally sit somewhere above the iron sights, with a less obstructed view, because the RD is 1/3 higher.
 
redneck said:
I got my first red dot today. I bought on of the Vortex Sparc II sights that Brownells had on sale for $125. Overall the sight seems nicely finished, it came with extra screws, 2 mounts and a spacer, and 2 batteries. It mounted easily and seems solid and I didn't have too much trouble getting it on target. The adjustment clicks are pretty mushy but still usable. 1 MOA clicks are hard to get used to when you are used to 1/4 MOA but I got it on paper.

The dot itself sucks. Its pretty much a snowflake. Maybe an angry spider. It also seems much bigger than 2 MOA but I didn't think about the fact I had it on the highest setting during the little bit of shooting I did today. I have it on an M4 and don't really care for it for target use but I think for defensive purposes it will work out just fine.

My question is on how to properly use the co-witness set up. I thought that red dots were supposed to be basically parallax free, but I noticed that depending on my cheek weld the front sight moves in relation to the red dot quite a bit. I understand that if the battery were dead and I had to use it as an iron sight that I would have to keep the front sight centered in the optic, but if I am using the actual red dot, do I ignore the front sight? Or do I need to line the dot/spider/snowflake up with the front sight each time?
Click to expand...
You have astigmatism
 
Since you prolly have astigmatism you need to dump red dots completely and go to prismatic sights or lose the front sight and find a scope with true 1x power.
Or spring for an ACOG.
 
Long term I want to put a something in the neighborhood of a 1-4x scope on, but I can make this work until then.
 
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