Scope vs Red Dot vs Iron Sights - Expected Accuracy

[Charlie Martinez]

When I first purchased my AR 15 I shot it strictly with peep sights. I soon noticed that slightly sub 2 MOA, 5-shot groups (around 1.8") were about the best I could manage shooting both .223 and 5.56 ammo. Later purchased a red dot sight (my first) and found that aiming was easier but my groups remained pretty much the same as before. I usually only use scoped bolt action rifles when I shoot at 100-yards so I'm relatively new at using irons or red dots at that distance so my questions are:
1. Is my rifle at fault or are my expectations too high if I'm a bit disappointed that I am not shooting tighter groups using red dot or irons?

2. If a rifle shoots 2" groups with iron or red dot sights and all else is equal (ie rifle, shooter, ammo etc.) what groups would the same rifle be expected to shoot with a good quality scope?

 

[tbs]

I think your ammo is at fault. If your groups are the same with irons and red dot they're probably going to about the same with scope. I should add however 1.8" groups with an AR is not terrible, nor is it great.

 

[lysanderxiii]

From my experience, iron sights and red dots have about the same aiming error on the target, as most dots and front sights are about the same angular width (approximately 4 moa).

Magnifying scopes, because the target is magnified see reduced aiming error.

(and despite what you may have heard, 2 moa is not all that bad, (if you are being honest with yourself.)

 

[z7]

Most red dots have a 2 moa dot and most iron front sight posts are at least this large if not larger, so shooting a group smaller than the sighting mechanism seems to be quite difficult. The high power folks can do it, but they are very good, know their system. And use targets made for the sights, I.e the target helps


Many AR pattern guns are capable of 1.5-2 moa accuracy, and many a bit better, but the system, (ammo, shooter, sights, rest, hand guard …..) when combined can be tough to get that internet famous 1 moa group

A few questions for you to consider:

Do you want to use a scope all the time or is the scope for chasing groups?

Is the gun meeting your other goals, or d you want to chase groups with this gun?

If thr purpose of the gun is not chasing groups but is instead for general plinking/hunting/self defense/because I wanted the gun, is 2moa accurate enough?


I like chasing groups and working up really accurate hand loads, and I also have guns that I don’t do that with. My 16” AR load development was based in ~2” group with a red dot at 100yds, not overpressured but had good velocity Numbers, and that was good enough

My 308 I shoot in prs is 3/4” groups, low velocity spread.


I can’t answer question 2, you could probably get a bit smaller in group size with good (match) ammo and a magnified optic, but do you want that from your AR?

 

[CraigC]

...so shooting a group smaller than the sighting mechanism seems to be quite difficult.

It shouldn't be. The size is almost irrelevant. The most important factor is to match your target to your sights. What you need is a target picture that you can consistently duplicate. Your front sight might subtend several inches at 100yds but if you can consistently bracket it against a target of similar width, you can easily shoot groups much smaller, and should.

 

[GRIZ22]

From my experience, iron sights and red dots have about the same aiming error on the target, as most dots and front sights are about the same angular width (approximately 4 moa).

Magnifying scopes, because the target is magnified see reduced aiming error.

(and despite what you may have heard, 2 moa is not all that bad, (if you are being honest with yourself.)

Most of the rifles Carlos Hathcock made his name with rifles that could only shoot 2 MOA. 2 MOA is good.

 

[General Geoff]

(and despite what you may have heard, 2 moa is not all that bad, (if you are being honest with yourself.)

Yep, 2 MOA is excellent for a service grade rifle with service grade ball ammunition regardless of sight type.

Anyone who claims to shoot sub-MOA with regular ball ammo out of ANY rifle should be doubted.

 

[KristopheCraig]

Achieving sub-2 MOA groups with iron sights or a red dot at 100 yards is quite respectable for most shooters and rifles. While a good quality magnified scope can potentially improve group size, it's essential to manage expectations and recognize the inherent limitations of different sighting systems. Additionally, continued practice, refinement of shooting technique, and experimentation with different ammunition types can also contribute to improved accuracy regardless of the sighting system used.

 

[z7]

It shouldn't be. The size is almost irrelevant. The most important factor is to match your target to your sights. What you need is a target picture that you can consistently duplicate. Your front sight might subtend several inches at 100yds but if you can consistently bracket it against a target of similar width, you can easily shoot groups much smaller, and should.

I agree that it is possible, and many folks do it

I find it difficult without a target designed for the distance you are shooting, the large black circle targets used in high power are a good example

I salute any person who can pick up a standard rifle and print a 2” group at 100 yds with irons, I would struggle

 

[silicosys4]

The ability to bracket the target with the front post of your rifle is only as good as your eyes ability to contrast the front sight against the target. My eyes just aren't good enough to see the difference between 1" off a 1" bullseye at 100 yards and dead on. Same with red dots. When the dot is even 1moa, how good are your eyes at picking out the 1/2" of bullseye peeking around the dot to know you aren't dead on?
I do appreciate that a lot of shooters can make amazing shots with irons, but there were also a lot of aftermarket options for iron sights that were oriented towards target shooting with the acknowledgement that standard notch/post irons come with serious limitations for precision.

 

[CapnMac]

A magnifying scope's primary virtue is in being able to identify targets at longer distances.

To that end, as pointed out above, they can help reduce "aiming error" through that zoomed-in vision.

But, you could put a 20x scope on a 6MOA rifle and it's not going to become a 2MOA rifle. It might could be shot, by a talented user to, perhaps 4-5MOA, by reducing that aiming error.

 

[3Crows]

I have a moderate astigmatism and very, very early cataract. If the rifle is accurate, anything short of a optical sight will leave that accuracy on the table. No doubt for me:

1. SCOPE. Any scope, even a cheapo bubble pack scope.
2. Open sights if decent. Up close the ghost rings work nice. Buckhorn to 50 yards, yeah, okay.
3. Red Dot. 10 yards. Use it on my air rifle for up close 'night time 'dilla kill'n. (Sig medium priced RD).

 

[jmr40]

It shouldn't be. The size is almost irrelevant. The most important factor is to match your target to your sights.

This.

A scope helps you see the target better. If you're using iron sights and have a 1" aiming point at 100 yards you can't see where you're aiming. You can see the aiming point with a scope. But if you use a 6" aiming point at 100 yards and hold the front sight on the bottom edge of the aiming point every time group size can be pretty close to what you can do with a scope. If you have the sights adjusted to hit 3" above point of aim at 100 yards they will be grouped in the middle. As you go to longer ranges the aiming point needs to be larger. At 600 yards you'd have a 36" aiming point.

I still prefer a scope though. In the real world you can't always pick the size of your aiming point. And scopes help in low light. You need good light to shoot accurately with irons.

IMO a low powered 1-4X or similar scope is every bit as fast as irons or dots up close. And moving to more magnification helps you at longer range. I even prefer a scope in low light to a dot sight. To me the dot's biggest advantage is a smaller, lighter aiming device than a scope.

 

[Bill M.]

I certainly get smaller groups on my two high power rifles with a scope than with red dot or iron sights.

 

[jmorris]

1. Is my rifle at fault or are my expectations too high if I'm a bit disappointed that I am not shooting tighter groups using red dot or irons?

It could be one or both but might be neither.

Using iron sights, the target ideal for the range it is shot from can make a huge difference.

For example you couldn't see where to aim on a 50 ft target at the distances this one is intended to be shot from.





They can both be shot at accurately, just need to be the right distance from them, so the diameters are more helpful with centering.

 

[IALoder]

2moa with irons or a non magnified optic is pretty darn good if you ask me, let alone with ball ammo. If you're trying to shoot groups, a well magnified optic with a fine reticle and small aiming point is the best way I've found.

 

[DMW1116]

Somewhere I read a story about having several shooters try a course with and without magnified optics. The end average result of several shooters with match grade rifles was the group size increased about 1 MOA with irons over groups with a magnified scope. Now, that was for a group of pretty experienced shooters with very accurate rifles. It's possible your rifle wouldn't shoot much better with a scope. However, I'd guess you could expect a reduction of group size with a scope, though how much really depends on how good you are with iron sights. I get about a 3/4 MOA reduction in size between irons and scope. However, that is with targets geared toward iron sight use, hand loads for the rifles, aftermarket front posts (0.052" wide vs the standard 0.072" wide), and about 4 years practice on the same rifle.

 

[Charlie Martinez]

Thanks to everyone that responded.

This is my first AR and I am enjoying it more than any other center fire rifle I've ever shot. However my rifle is (or initially started as) a budget project to determine if an AR was right for me. Fortunately it turned out to be a great acquisition and I am really enjoying my time with it at the range.

I have made a couple of upgrades to the original rifle and the "budget" category may be rapidly fading. The first being replacement of the bolt. The original extractor started to malfunction (after about 400 rounds) and rather than replacing the extractor on the original bolt I found a good deal on a higher grade bolt. This solved the problem and I haven't had any feeding or extraction failure ever since. Later a friend offered me a red dot to keep if I liked it and that worked out well but although I expected accuracy from the bench to improve it didn't. The last improvement was replacement of the mil spec trigger with a drop in one stage unit. Again to my surprise once bench rest accuracy at 100 yds. was not improved by much (if any).

Adding the red dot and replacing the trigger did not improve groups so I began to wonder if maybe my rifle was inherently incapable of performing to 1 MOA level. My only other and final way to find out was to see what would happen if I mount a high magnification scope. However I don't intend to permanently mount a scope on this rifle and wasn't going to waste my time experimenting with one if I was told that it was the gun not the sights.

Like I said earlier I like my rifle as is and if it can't shoot 1 MOA I'm still going to be happy with it but as a matter of curiosity it would be good to know its accuracy potential.

 

[doubleh]

My experience has been irons least accurate, red dot somewhat better, and scopes best. Even back in dinosaur days long before red dots were even thought of I was more accurate with a scope. I never had any sight problems to deal with until getting far sighted in my '50's. Then things can become annoying with irons. Peep sights are close to the red dot although not as fast in my case. I see this as choose what you prefer that will do the job you want, get out and shoot, and enjoy yourself. You might even improve while doing so.

 

[DMW1116]

My rifles are only MOA capable with tuned hand loads. Even then, if I shoot 10 shots they won’t stay under MOA. If you aren’t a hand loader, 2 MOA is nothing to sneeze at, even with a scope.

 

[trackskippy]

I think the problem here is, there are broad spectrum of things being discussed here, and the expectation that one thing will solve all of them. I don't think that's being realistic.

Everyone when you talk to them, seems to have a gun that shoots bug holes until you ask them to show you, right here and now, without preparation and/or a bench using that box of ammo you just bought at Walmart.

Ive shot enough military and HP type matches in the past to know that a 2" group from issue ammo shot from a field position (which one tends to usually be very important here too ) at a 100 yards, is very much doable using the iron sights on a M1, M14, or M16, etc. Most issue ammo is spec'd to about 2-3moa and I think the guns, as long as they arent worn out specimens, are in about the same realm.

Ive found, with the red dots on my long guns, most of which have a 4moa dot, they will shoot similar to the irons, given an aiming point that can be repeated with regularity. The advantage of the red dots though, isn't in the normal points type target shooting spectrum.

Scopes are a different critter, and the type of scope and its intended use, can vary things. Ive never really been a big fan of scopes until more recently, and have come to have a different opinion of them now, especially the LPVO type. Most of my shooting over the years has been mostly iron, and then red dots, and shooting from field positions than trying to shoot bug holes over time from a fixed bench or rest.


I think if you want to figure this all out, you just have to do it the old fashioned way, and that's going to be a lot of work, and rounds down range. One thing at a time until you figure each one of them out too baby.

 

[PapaG]

Brian Pearce had an article in Rifle where he compared open, peep, and scope sights on the same rifle. I don’t remember the specifics but I seem to think he found the peep and scope very close at 100.
My experience, fifty years ago, in BPCR shooting was that my groups using peeps were 25% of those with peeps at 100 and couldn’t compare at 200 as I couldn’t get the opens to print on the target. Same results with the Civil War musket. In fact, with high end aperture sights I was able to effectively compete in bench rest matches.
Now, my eyes demand a scope for beyond 50 yards.

 

[MZ5]

I get terribly amused when folks try to defend iron sights (against magnifying riflescopes) by telling a person they must match their target to the distance at which they're shooting. I'm sure this is due to how I approach a rifle, or any firearm. I may, occasionally, shoot my rifles for groups on paper, but that is not why I have any of my rifles. Every one of them is a 'working' gun, or at most an NRL-type (PRS-type) play toy, too. So, the entire concept of asking an elk (or javelina or bear or squirrel or...) I may see out there to please move along and quickly send in another of a different size, that's better suited to how far away from me he is, is extremely amusing!

 

[Telekinesis]

Lots of good discussion on sights and particularly accuracy in relation to the target being used, but I want to take a shot at another side of what it seems you’re asking.

However my rifle is (or initially started as) a budget project to determine if an AR was right for me.

[…]
I have made a couple of upgrades to the original rifle and the "budget" category may be rapidly fading.

Adding the red dot and replacing the trigger did not improve groups so I began to wonder if maybe my rifle was inherently incapable of performing to 1 MOA level. My only other and final way to find out was to see what would happen if I mount a high magnification scope. However I don't intend to permanently mount a scope on this rifle and wasn't going to waste my time experimenting with one if I was told that it was the gun not the sights.

It seems like you’re asking if your particular rifle is capable of shooting to a specific standard, but you’re not telling us what the rifle is. That’s not an answer any of us can give you. That’s like asking “I have this car, will it win an autocross race?” without telling us if you have a race prepped Mita or a F550 work truck. And (no offense) but we also don’t know if you are capable of meeting that accuracy standard as a shooter.

Generally I would not expect a budget rifle to consistently maintain 1 MOA, especially if you are using bulk ammo. It’s not impossible, but without knowing more I would say it is unlikely. Even though you’re putting money into various components, the heart of the gun is still a budget gun. It is quite possible to have a very expensive budget gun.

The only way to know if your rifle, with your ammo, and with you behind the gun is capable of 1 MOA is to shoot it. And most likely you’ll need to shoot it with a magnified optic in order to have the best chance of you performing at your best and minimizing the potential for error. The scope doesn’t change anything about the weapons mechanical accuracy, but it lets the shooter minimize their error.

 

[Telekinesis]

I get terribly amused when folks try to defend iron sights (against magnifying riflescopes) by telling a person they must match their target to the distance at which they're shooting.

I’m not sure people are necessarily defending iron sights, rather they’re saying that if your pursuit is to find the ultimate mechanical accuracy of the firearm and you are only using iron sights, using a target designed for the purpose can help.