Position of optic on a carbine

[halfmoonclip]

I've some experience with scopes on hunting rifles, but red dot optics are a new thing entirely.
Have a Romeo 5 on a Scorpion, and a Holosun on an AR9.
Happy with them so far, but they are mounted more toward the rear of the firearm.
I see all the high speed/low drag guys mounting optics directly over the E-port, or even further forward.
What is the reasoning behind this?
Thnx,
Moon

 

[Varminterror]

Farther back = more FOV within the optic, but more field obscured BY the optic. Farther forward = less field obscured, but less FOV within the optic. Since most of these RDS’s are 1x, non-magnified, the FOV within the window is largely continuous with the external field, so most folks prefer to reduce their obstruction and see more of the field organically; more head up shooting style instead of only seeing the world through the optic.

 

[BoBo522]

Mine is over the ejection port so I have sufficient room for a 3x magnifier behind it.

 

[Chuck R.]

My carbines with RDS are set up for defensive use so mine wear cantilever mounts that put the RDS as far FWD as possible. I prefer to obscure the least amount possible of the tgt area.

 

[rbernie]

I will also admit that I prefer a slightly muzzle-heavy balance; a lightweight barrel is nicely offset by a WML and a RDS mounted as far forward as I can get it on the receiver.

 

[greyling22]

typically they are more or less over the ejection port, subject to personal preference.

 

[jmorris]

To add to the spot on information in #2, the design of the optic also matters, sometimes a LOT as far as obscuring view.

Like this, for example.



I think the discontinued Leupold mk4 CQ/T was the absolute worst I have ever looked through in this reguard.

 

[chicharrones]

To add to the spot on information in #2, the design of the optic also matters, sometimes a LOT as far as obscuring view.

Like this, for example.

View attachment 984338 View attachment 984339

I think the discontinued Leupold mk4 CQ/T was the absolute worst I have ever looked through in this reguard.

That upper replica view is of a prism sight? Can't really slide that forward out of eye relief range anyway.

 

[Zerodefect]

All the way forward like Chuck has, then I often move them back just a hair. No more than one inch back.
Depends on the model.

My Eotech is all the way forward and mounted low. 100% cowitness. Eotech's work great with iron sights. In very intense summer daylight, I prefer irons.

My Aimpoint Comp M3 is in a cantilever mount centered over the ejection port. High mount, lower 1/3rd cowitness. I use BUIS a bit less with this optic.

Trijicon Credo 1-8x in Larue LT104. I don't use the BUIS at all with this optic.

 

[AK103K]

I use cantilever mounts at the furthest most point on the upper itself, which puts the front half of the sight just forward of the upper. Im still using the old Aimpoint M2's.

I usually leave the front cover closed too, as it allows me to set the dot to a good brightness so its not too bright indoors or in lower light, and its not lost in bright light outside. Opens in a flick if I feel the need.

The sight is always on too, so I never have to fiddle with it.

 

[taliv]

as far forward on the receiver as possible for reasons mentioned above, plus sometimes you need the room behind it for NV or magnifier

 

[WestKentucky]

The dot size is a reason to move forward. With the RDS right up in your face the dot can seem rather large. Moving it further away makes the dot seem smaller, and if your going for anything resembling precision then you want the most finite dot as possible for best aim. There’s also the thought for home defense that a large dot can work for “shoot now” purposes as it matters less what part of the dot is on target because as long as the dot is on something it’s a hit. Personally, I like a RDS ever so slightly forward of the ejection port so that it’s out of the way for clearing jams and out of the way of ejecting brass.

 

[LoonWulf]

That upper replica view is of a prism sight? Can't really slide that forward out of eye relief range anyway.

Yeah, my Bushnell like is last slot on the receiver, just to get the eye relief where I want it.

 

[Phaedrus/69]

I guess I'm the outlier. I prefer my Aimpoint further back, almost where you'd mount a conventional scope. No NVG or magnifier on my RDS-equipped long guns, though.

 

[BCR#1]

Thanks to the OP for bringing up this subject. I have dots on all of my rim/center fire MSR types and will try different rail positions.

Bill

 

[whughett]

Personal preference perhaps. I can not shoot with both eyes open so I need to look directly into the aiming device so it seems to work for me as close to the eye as possible

 

[Chuck R.]

Thanks to the OP for bringing up this subject. I have dots on all of my rim/center fire MSR types and will try different rail positions.

Bill

Honestly the best method!

I've taken several defensive carbine classes and shoot my PCC in matches. I've gravitated to "what works for me".

Cool part about a flat-top AR is that it's easy to move the optic. I'd run some common drills (IE. El Presidente, Box Drill etc.) on a timer. On standard drill distances the delta in the zeros won't be bad enough to throw off results. I suggest a timer because a defensive carbine is all about accuracy AND speed. Accuracy might be a wash, but the delta in tgt acquisition between mounting locations could be significant.

 

[Zerodefect]

Generally, I move the sight back so I can see through it easier. Not through the glass, but through the body of the scope. Bindon aiming concept. If the scopes too far forward, like how people used to put it on the rails, it's body almost blocks both of your eyes, and that sucks.

There's always a sweet spot.

Like how you can see through your nose. When you look hard left or right.

 

[AK103K]

Generally, I move the sight back so I can see through it easier. Not through the glass, but through the body of the scope. Bindon aiming concept. If the scopes too far forward, like how people used to put it on the rails, it's body almost blocks both of your eyes, and that sucks.

There's always a sweet spot.

Like how you can see through your nose. When you look hard left or right.

I find the optic mounted more to the rear to block more of my vision, especially my peripheral vision than one mounted forward. Never had any issues looking through the tubes with them forward either.

That Bindon Aiming Concept is exactly how the old OEG type red dots work, and how the red dots with the front covers closed work. Your strong eye sees the dot, and your weak eye sees the target, and your brain puts them together.

With the Aimpoints mounted basically just forward of the upper, with the rear face centered on the ejection port, I really don't even notice the cap was closed be at all, and just see the dot where Im looking on the target. If you didn't close youre weak eye, you wouldn't even know the front cap was closed.

The only time I really open the front covers on mine is when I turn the dot brightness down, making the dot appear smaller/finer, trying for a more precise aiming point at longer distances.

 

[Zerodefect]

Yeah, that's the trick.

Focus on the target, and the Aimpoints body should mostly disappear. My slightly more forward mounted Eotech, not as much.

I also close my front cap on the Aimpoint to teach people this. It also carries over to tactical scopes. A very bright reticle on a scope like the Trijicon 5-20x Accupoint will allow up close 1x easy. Just concentrate on the target and wink the scope eye. Or even go as far as closing the front cap.

 

[halfmoonclip]

Thanks to varmin', #2, for a really comprehensive explanation. jmorris, your pics illustrated some of varmin' points, and let me see the potential for refractive sights...all of a sudden, I understand.
I'll have a look at the position of my red dots, which are partially over the E-port, to the rear.
Noticed a poster mentioned just leaving red dots turned on. I realize they have a motion sensor, and 'go to sleep' when left undisturbed. Anyone leaving their dots turned on?
Thnx,
Moon

 

[halfmoonclip]

Honestly the best method!
.... On standard drill distances the delta in the zeros won't be bad enough to throw off results. I suggest a timer because a defensive carbine is all about accuracy AND speed. Accuracy might be a wash, but the delta in tgt acquisition between mounting locations could be significant.

Have to concur on "what works for me". 'Splain the "delta" business, please?
Thnx,
Moon

 

[taliv]

people who have aimpoints leave their dots on and change their batteries every few years

 

[Chuck R.]

Have to concur on "what works for me". 'Splain the "delta" business, please?
Thnx,
Moon

Sorry, should have used an upper cased "D", but Delta generally means "difference".

 

[Zerodefect]

My Aimpoint doesn't even turn off. The lowest (off) setting is for night vision.

I generally turn it off/down for storage. Beware that they need their battery removed and put back in from time to time. The surface of the battery seems to invisibly corrode or something, and it won't turn on.