Red Dots on Carbines: What is the Right Sight Height for Me?

[outrider58]

I posted this YouTube in a thread a while back and thought this topic might help others decide. He does a really good job laying out the genesis of red dot sight mounts and their ever increasing heights in use today.

I have really taken to higher sight mounts. They seem to allow for a more natural presentation, especially where it concerns SBRs and braced pistols. Guns inherantly adaptable to close in, short range work.

Give it a watch...

 

[MattFinals718]

I've always preferred red dots co-witnessed with the front sight in the lower 1/3rd field of view (and I also prefer to run fixed front sights on all of my carbines with reflex optics). I discovered that preference with my Aimpoint PRO, which I've had for a while now. When I first set it up on my DDM4, I briefly tried removing the spacer in the mount for an absolute co-witness, and discovered that the front sight tends to obscure too much of my view and/or get in the way of the dot.

I also admit that I'm not sure if I'd care if I was running the red dot on any other type of gun (e.g., a shotgun), but I currently only have red dots on my ARs.

 

[outrider58]

I've always preferred red dots co-witnessed with the front sight in the lower 1/3rd field of view (and I also prefer to run fixed front sights on all of my carbines with reflex optics). I discovered that preference with my Aimpoint PRO, which I've had for a while now. When I first set it up on my DDM4, I briefly tried removing the spacer in the mount for an absolute co-witness, and discovered that the front sight tends to obscure too much of my view and/or get in the way of the dot.

I also admit that I'm not sure if I'd care if I was running the red dot on any other type of gun (e.g., a shotgun).

I do like RDSs on my shotguns, but only in a hunting application(turkey). I don't like SGs for home defense.

 

[smdub]

I watched that video on the other thread. I want my 18m back. I understand the point w/ NODs but the video is lacking... just about everything. Could have been 1/4 as long if he just took out all the video of him shooting. Then its just a presentation of a couple tall mount options. He goes into absolutely NONE of the downsides of a tall optic beside a quick mention that you won't like it shooting prone. So while his points might be valid, its a very biased presentation. That always makes me dismiss most of the points made.

I prefer fairly low sights. Same presentation w/ irons, shotguns, prone w/ scopes, etc. Lift the gun to your cheekbone, open your eyes and its there.
I have no NODs (yet). If I did, I would setup one rifle to work with them.

 

[MattFinals718]

I do like RDSs on my shotguns, but only in a hunting application(turkey). I don't like SGs for home defense.

If I ever get another shotgun besides my pistol-grip Mossberg, which I never use for much, I'll have to play around with where I put the optic. Then again, I have the same problem as you - I don't use mine for home defense, and I don't hunt, so I probably won't get another shotgun any time soon.

 

[King Chicken]

you won't like it shooting prone

Depends on the height of "tall" mount. Right? I've read on other sites 1.7-1.9" is absolutely the limit for comfort prone. The unity everyone has is 2.26? I don't know.

As Mr. Miyagi taught me. One must have balance or something. Something about wax too.

 

[outrider58]

I watched that video on the other thread. I want my 18m back. I understand the point w/ NODs but the video is lacking... just about everything. Could have been 1/4 as long if he just took out all the video of him shooting. Then its just a presentation of a couple tall mount options. He goes into absolutely NONE of the downsides of a tall optic beside a quick mention that you won't like it shooting prone. So while his points might be valid, its a very biased presentation. That always makes me dismiss most of the points made.

I prefer fairly low sights. Same presentation w/ irons, shotguns, prone w/ scopes, etc. Lift the gun to your cheekbone, open your eyes and its there.
I have no NODs (yet). If I did, I would setup one rifle to work with them.

He's long winded because he is an instructor. I can't give you your 18 minutes back, but your next breakfast is on me.

 

[Blaster229]

Watch and learn.

 

[King Chicken]

Watch and learn.

Guy said tall optic mount let's him see not only 360 degrees but also 720 degrees. I'm getting one for sure.

 

[erwos]

Some thoughts... keep in mind I'm an action shooting guy, so my perspective is heavily skewed in that way:
1. "Normal" scopes: absolute co-witness height to lower 1/3.
2. LPVOs / prisms: lower 1/3 to 1.7.
3. Reflex sights (no planned NV use): lower 1/3 to 1.93.
4. Reflex sights (planned NV use): 1.93 to 2.26.

Lower 1/3 tends to be fine for me for going fast if NV isn't involved. I know a lot of dudes have made the move to 1.93, and I think that's great, too, it just doesn't seem to be an issue for my shooting quite yet.

(If NV's in the mix, give me that big high window, absolutely.)

 

[outrider58]

To reiterate, the higher setups are mainly intended for CQB guns. There are other practical applications though.

 

[MattFinals718]

Watch and learn.

To reiterate, the higher setups are mainly intended for CQB guns. There are other practical applications though.

The irony is that in many ways, this is a return to the past: When red dots first entered widespread usage with U.S. Special Operations Forces (mid/late-1980s), they were typically mounted on AR carbines which had fixed carry handles (since flattop uppers weren't common yet, especially on AR carbines). That meant that the optics had to be mounted on top of the carry handles and sat pretty high relative to the bore axis, which I'm sure worked well in CQB, especially when wearing the AN/PVS-7 (the best NODs available at the time). But then the flattop M4 Carbine came into service in the mid-90s, and then the Aimpoint CompM2 (M68 CCO) with an absolute co-witness mount entered service by the early-2000s, and so the higher-mounted optics went away. Guess some folks are now re-discovering that what was done in the past actually worked pretty well...

 

[erwos]

That meant that the optics had to be mounted on top of the carry handles and sat pretty high relative to the bore axis, which I'm sure worked well in CQB, especially when wearing the AN/PVS-7 (the best NODs available at the time).

The PVS-7 is extremely hard to use for passive aiming no matter what sight height your optic is at, due to how the single tube is positioned. Also not sure how well the early Aimpoints worked with NV and light transmission. All of which is to say, I'm skeptical that what you're describing was the reality of the situation back then in terms of "working well". As far as I am aware, NV aiming doctrine until mid-GWOT was basically "go active" or "use an NV scope".

 

[smdub]

Optics and NV were bolt on bulky afterthoughts on those era rifles.

 

[lazarus]

I've always preferred red dots co-witnessed with the front sight in the lower 1/3rd field of view (and I also prefer to run fixed front sights on all of my carbines with reflex optics). I discovered that preference with my Aimpoint PRO, which I've had for a while now. When I first set it up on my DDM4, I briefly tried removing the spacer in the mount for an absolute co-witness, and discovered that the front sight tends to obscure too much of my view and/or get in the way of the dot.

I also admit that I'm not sure if I'd care if I was running the red dot on any other type of gun (e.g., a shotgun), but I currently only have red dots on my ARs.

I prefer absolute cowitness, but I also run MBUS flip-ups. So it normally isn't obscuring my view at all. Sig Romeo 5 is my favorite. I ran Bushnell 25s for a few years. Because I am cheap and I Just wanted one that "worked". I finally realized, just too dim in full daylight on a sunny day and questionable quality. Yeah the Sig is not the most rugged awesomest thing. But I've banged it by accident a couple of times really hard and it is still ticking. And it is bright enough in full daylight to see fine.

 

[Bountied]

I prefer absolute cowitness, but I also run MBUS flip-ups. So it normally isn't obscuring my view at all. Sig Romeo 5 is my favorite. I ran Bushnell 25s for a few years. Because I am cheap and I Just wanted one that "worked". I finally realized, just too dim in full daylight on a sunny day and questionable quality. Yeah the Sig is not the most rugged awesomest thing. But I've banged it by accident a couple of times really hard and it is still ticking. And it is bright enough in full daylight to see fine.

I am like you, absolute co-witness and Romeo 5s are my go to. Here is a video of a torture test of the Romeo 5. Long story short it's pretty tough. They shoot it with a shotgun remount it and it's still on. I'd say that's pretty good.

 

[MattFinals718]

The PVS-7 is extremely hard to use for passive aiming no matter what sight height your optic is at, due to how the single tube is positioned. Also not sure how well the early Aimpoints worked with NV and light transmission. All of which is to say, I'm skeptical that what you're describing was the reality of the situation back then in terms of "working well". As far as I am aware, NV aiming doctrine until mid-GWOT was basically "go active" or "use an NV scope".

That's a good point, and you're probably right - the PVS-7's design is really not conducive to passive aiming at all. But my main point is: CQB optics in those early days sat high because they were mounted on AR carry handles, and nowadays, there's a trend towards them being mounted high again, albeit for different reasons than in the past.

I prefer absolute cowitness, but I also run MBUS flip-ups. So it normally isn't obscuring my view at all. Sig Romeo 5 is my favorite. I ran Bushnell 25s for a few years. Because I am cheap and I Just wanted one that "worked". I finally realized, just too dim in full daylight on a sunny day and questionable quality. Yeah the Sig is not the most rugged awesomest thing. But I've banged it by accident a couple of times really hard and it is still ticking. And it is bright enough in full daylight to see fine.

I actually don't mind absolute co-witness when I'm running one of my EOTechs as much as I do when I'm running a red dot, because I usually run flip-ups with EOTechs. With red dots, the FSP helps me find a point of reference, because I often have to run the dot on a low setting to compensate for my astigmatism.

And I've heard great things about the latest SIG Romeos - some YouTubers I watch are calling them the best red dots on the market right now.

 

[erwos]

That's a good point, and you're probably right - the PVS-7's design is really not conducive to passive aiming at all. But my main point is: CQB optics in those early days sat high because they were mounted on AR carry handles, and nowadays, there's a trend towards them being mounted high again, albeit for different reasons than in the past.

I'm going to disagree again here. Early reflex sights were NOT all mounted high. The IDF's use of gooseneck mounts for the Elbit Falcon (one of the earliest reflex sights) is well-documented, as is the US Army's use of gooseneck mounts with the M68 CCO. While I have no doubt that there were some mounted high on carry handles, the stereotypical high carry handle mount was actually used for ACOGs and Colt-style scopes which had more limited eye relief.

 

[MattFinals718]

I'm going to disagree again here. Early reflex sights were NOT all mounted high. The IDF's use of gooseneck mounts for the Elbit Falcon (one of the earliest reflex sights) is well-documented, as is the US Army's use of gooseneck mounts with the M68 CCO. While I have no doubt that there were some mounted high on carry handles, the stereotypical high carry handle mount was actually used for ACOGs and Colt-style scopes which had more limited eye relief.

If you're talking about the era when the M68 CCO entered service (late-90s/early-2000s), we're not talking about the same thing. I'm talking about the 1980s, when the first Aimpoints started entering use with U.S. SOF. I don't believe gooseneck mounts were in use at the time (don't even know that they existed). All the pics I've seen of the Colt 723s used by SFOD-D/CAG and 727s used by 75th/NSW show the optics mounted atop the carry handle.

Think also of the H&K claw mounts for optics, which kept the optic (whether it was reflex or magnified) pretty high above the bore axis. (And back in those days, H&Ks were also heavily used in SOF units.)