Where to Position Dot Sight on Rail?

[JDinFbg]

I just received and used the first dot sight I've ever owned on my Winchester '94 (my old eyes and iron sight are no longer compatible). The dot sight is a Burris FastFire 2 reflex sight with a 4 MOA dot. It is mounted on a no-drill picatinny rail and sits low enough to maintain a good cheek weld during shooting. My only experience with dot sights before now was doing some limited shooting with a friend's AR with a 2 MOA dot sight. I found the 2 MOA dot hard to see and acquire under bright daylight conditions. I wanted something usable under all light conditions for shooting feral hogs at ranges of 25-100 yards, so was only looking for minute-of-pig resolution.

I decided to mount the sight as far back on the rail as possible in order to maintain the maximum field of view through the sight lens. However, on my first shooting outing to zero in the sight, I noted the 4 MOA dot totally covered an 8" diameter target at 100 yards. My thought is that a 4 MOA dot should cover a 4" circle at 100 yards. So, now I'm wondering what dot size really means in a dot sight? Are dot sizes specified based on the sight being positioned some certain distance from the shooter's eye?. I'm wondering if moving the sight forward on the rail will result in the dot appearing smaller and closer to the specified 4 MOA size? The rail will allow me to move the sight about 5-6" farther forward.

 

[Corpral_Agarn]

I like my dot sights furthest forward on the upper receiver.

I prefer a 2MOA dot for my purposes.

Example:

 

[Varminterror]

The dot should ideally be as far forward as possible.

The dot shouldn’t shrink as you move it forward - not relative to the target at least.

 

[pblanc]

I also like to have red dot sights mounted relatively far forward. If you shoot with both eyes open, your downrange view will not be limited by the sight tube. In fact, with the sight farther forward you will be able to see around it with your non-shooting eye better.

 

[MistWolf]

Mount your red dot sight at whatever distance works for you. I like my RDS closer to my eye than most people. The further from your eye, the harder it is to find and center the dot and the smaller the field of view.

The closer to your eye, the easier to find and center the dot and the larger the field of view. If it's too close, the thicker the tube appears which obscures your view.

Play with it until you find the right distance.

 

[Ed Ames]

It “should” be as far forward as possible.

As far as field of view, here’s a fun bit of trivia: some of the tube style red dots come with (came with?) an opaque cover for the objective lens (side closest to the muzzle) and a windowed cover for the ocular side (closest to you), both on tethers. The reason? The sights are usable that way, covers on. Just keep both eyes open and your non-scope eye shows you the target, your scope eye shows you the dot, and your brain merges the two. I think the idea was that if you found yourself in an unexpected firefight you could start responding without delaying to remove the covers. If you can do that with a red dot with a cover over it so you can’t see through it at all, I’m pretty sure that the little frame isn’t going to block your field of view. Getting it as far forward as possible keeps the sight from blocking your vision as much.

Your gun should be set up so that when you mount it, the sights are aligned. If you have a stock set up for iron sights but the red dot is a bit higher you may need a pad to help with cheek weld. If everything is right, finding the dot should be zero effort. You should not need to hunt for the dot any more than you need to hunt for a sight picture with iron sights. If they aren’t lined up even you mount the gun, something is wrong.

 

[MistWolf]

...Your gun should be set up so that when you mount it, the sights are aligned. If you have a stock set up for iron sights but the red dot is a bit higher you may need a pad to help with cheek weld.

If the red dot is higher than the iron sights, using a taller cheek pad will make using the iron sights more difficult.

If everything is right, finding the dot should be zero effort. You should not need to hunt for the dot any more than you need to hunt for a sight picture with iron sights. If they aren’t lined up even you mount the gun, something is wrong.

This assumes the shooter sticks with conventional shooting positions. Shooting from unconventional shooting positions (such as rollover prone) means solid cheek welds aren't always obtainable.

As far forward as possible is the conventional thinking, but not best for everyone.

 

[Ed Ames]

If the red dot is higher than the iron sights, using a taller cheek pad will make using the iron sights more difficult.

Yep. If the sights aren’t set up to cowitness, he’s going to need to make a choice of which sights are easier to use. If he just spent $$$ on a red dot he probably wants to use it so he should set up to use it properly. A removable cheek pad can be removed if he decides his iron sights need to be primary for some reason.

This assumes the shooter sticks with conventional shooting positions. Shooting from unconventional shooting positions (such as rollover prone) means solid cheek welds aren't always obtainable.

Using that “logic” you could as easily say “Installing sights assumes that the shooter sticks with conventional aimed fire. Shooting blindly into the air means not using sights.” I mean, it’s true but who really cares? Even if a shooter sometimes uses an unconventional position, the rifle should be set up properly for normal use.

As far forward as possible is the conventional thinking, but not best for everyone.

I alluded to that with the quotes around the word should. However, I’m honestly curious to know who it would be wrong for. I’ve tried a range of mounting positions and I don’t think it makes that much difference but I can’t think of any real (not contrived for the sake of Internet argument) reasons for actively wanting it mounted closer to the eye.

 

[MistWolf]

Yep. If the sights aren’t set up to cowitness, he’s going to need to make a choice of which sights are easier to use. If he just spent $$$ on a red dot he probably wants to use it so he should set up to use it properly. A removable cheek pad can be removed if he decides his iron sights need to be primary for some reason.

Just to make sure we're on the same page, we're talking about absolute cowitness versus 1/3 lower cowitness. A cheek pad isn't needed for either.

Even if a shooter sometimes uses an unconventional position, the rifle should be set up properly for normal use.

No one is talking about shooting blindly in the air. We're talking about finding the dot. With the RDS further from the eye, it's harder to find the dot. This is an important point when shooting from positions where getting a normal check weld may not be possible.

I’m honestly curious to know who it would be wrong for. I’ve tried a range of mounting positions and I don’t think it makes that much difference but I can’t think of any real (not contrived for the sake of Internet argument) reasons for actively wanting it mounted closer to the eye.

Didn't say a forward mounted RDS would be wrong, just that it may not always be best. It may or may not be a big difference. But it's enough difference for me that, after shooting with the RDS in different positions, I prefer it to be closer to my eye than the accepted convention.

Everyone has to decide for themselves where to mount an RDS. Go shoot the AR and see what works for you. The biggest reason to push an RDS forward is to have room to mount a magnifier.

 

[Ed Ames]

Just to make sure we're on the same page, we're talking about absolute cowitness versus 1/3 lower cowitness. A cheek pad isn't needed for either.

I have no reason to suppose that’s true. The OP didn’t say anything to imply it was cowitnessed. It’s a lever action with a scope base rail. I’ve done similar (with a deltapoint instead of a FastFire but from a distance you’d be hard pressed to tell those apart, they are the same form factor) and it did not cowitness at all. My own experience with a very similar setup is that a non-cowitness red dot on a lever gun resulted in a configuration that could be used “well enough” without a cheek pad, but very much benefited from a slip-on pad.

If it is cowitness, great, they still should do whatever they can to make sure the sights line up naturally when they mount the rifle, and if they regularly do some other sort of hold that makes alignment hard I guess they need to practice that until it is automatic too.

No one is talking about shooting blindly in the air. We're talking about finding the dot. With the RDS further from the eye, it's harder to find the dot. This is an important point when shooting from positions where getting a normal check weld may not be possible.

Well, no, you are talking about a shooting scenario that will possibly make something harder if a person happens to use it and happens to have a hard time with it, as a justification for making the gun harder to use all the time. I think that’s about the same as arguing for leaving the sights off because you don’t use them when shooting randomly in the air... which is another way of saying it doesn’t make sense.

Didn't say a forward mounted RDS would be wrong, just that it may not always be best. It may or may not be a big difference. But it's enough difference for me that, after shooting with the RDS in different positions, I prefer it to be closer to my eye than the accepted convention.

Everyone has to decide for themselves where to mount an RDS. Go shoot the AR and see what works for you. The biggest reason to push an RDS forward is to have room to mount a magnifier.

What AR?

 

[MistWolf]

...Well, no, you are talking about a shooting scenario that will possibly make something harder if a person happens to use it and happens to have a hard time with it, as a justification for making the gun harder to use all the time.

I find a closer mounted RDS easier to use in all cases than if it's mounted further away.

What AR?

Ha! I am chagrined to admit I overlooked we're talking about an RDS on a lever action.

Bottom line- Each shooter must determine for themselves what works best.

 

[Ed Ames]

Bottom line- Each shooter must determine for themselves what works best.

I agree 100%.

 

[Odd Job]

I tried a number of positions using a 3MOA Burris Fast Fire III red dot on a SIG522. In the end I found it better to put the dot as far forward as possible for two reasons:

1) The housing obstructs less field of view
2) For that particular dot, you can get on target faster if the dot is forward, at least on that rifle.

I had a 1/2" Yankee Hill Machine riser on my 522 which gave me a little more room to mount the dot further forward.

 

[TonyAngel]

If it is you intention to look and "see" through the optic tube or frame, then mounting it as far back as possible will give you the best "field of view," but will also make the dot seem much larger compared to the target. This is when you need the smallest dot size possible. I shoot with both eyes open so "field of view" through the optic is a non issue. I keep my red dot as far forward as I can get it on the rail and don't even see the optic while I'm shooting. I've found that the farther out on the rail that you have the optic, the easier it is to pick up the dot.

 

[MistWolf]

If it is you intention to look and "see" through the optic tube or frame, then mounting it as far back as possible will give you the best "field of view," but will also make the dot seem much larger compared to the target. This is when you need the smallest dot size possible.

I don't find either assertion to be true with any of our tube type RDS. When mounted too close, the rear lens is much larger than the front lens due to perspective and the tube looks thicker, obscuring the view.

Close up or far away, the dots look the same size to me.

I shoot with both eyes open so "field of view" through the optic is a non issue.

I've always shot with both eyes open, regardless of sight type.

I keep my red dot as far forward as I can get it on the rail and don't even see the optic while I'm shooting. I've found that the farther out on the rail that you have the optic, the easier it is to pick up the dot.

As an experiment, I mounted an RDS at the end of a barrel and found it harder to find and center the dot because less of the field of view is visible. If I was the least bit sloppy mounting the rifle, the dot would be lost and I had to hunt for. The closer the RDS is to the eye, the more of the field of view the eye can see.

However, as I've said from the beginning- it's all individual.

 

[Ed Ames]

There might well be differences in technology too. Not all RDSs use the same technology. I’m not sure how much of a difference it makes but it might contribute to differences in what works for different folks.

 

[MistWolf]

I think the real difference is how each of our brains work. As a kid, I shot thousands of BBs through a Crossman M1 carbine BB gun with an aperture sight. I see an RDS as nothing more than a large ghost ring with a floating red dot.