Red Dot Zeroing/Efficient Optics & Attachments

[WelcomeToTheGunZone]

Hey everyone, so i wanted to ask a couple questions about my AR-15 5.56 chambered rifle. But before i do, i'll give the specs for context.


So it's a custom built setup, with a pre-built 16" barrel length upper receiver (5.56 obviously), a front post sight base, factory M4 style plastic handguard, a small picatinny rail from the rear of the upper receiver that ends right before the handguard, flip-up backup sights on the rear of the rail, and a Romeo5 red dot on a Monstrum 3.5 in. adjustable riser with quick release arms for aiming comfortability.


My first concern is that i noticed when i try to zero in the red dot, there's a big difference between zero'ing at say 10 or 15 yard vs 25 to 50. And i'm assuming this has to due with the height of the red dot. Is there any way to lessen this difference without sacrificing comfortability? Is it worth worrying about or trying to resolve it?

My next curiosity is trying to optimize the setup by say adding a flip-mount magnifier for acquiring further targets better. Is this worth it to add a magnifier to make it easier to acquire longer range targets?

My last question is just a general catch-all on general improvements or things that would be worth doing to the rifle to make it overall better to use or more effective/efficient. What do you all suggest are the best additions/improvements/adjustments to make to a rifle such as this?

 

[Rob228]

My first concern is that i noticed when i try to zero in the red dot, there's a big difference between zero'ing at say 10 or 15 yard vs 25 to 50. And i'm assuming this has to due with the height of the red dot. Is there any way to lessen this difference without sacrificing comfortability? Is it worth worrying about or trying to resolve it?

That is normal and that is all because of the height of the red dot over the axis of the bore. If you are using it for anything close, just know how much you'll have to hold over to put the round where you want it. It is really only an issue for small targets up close.

 

[Houndog]

A tremendous amount has been written about zeroing a CQB rifle. I generally zero any rifle with a red dot at 50 yards. As you've discovered, this will result in your shots being about 2" low at 25 yards. And will result in your shots actually being high at 100 yards. Generally, depending on ammo and the length of your barrel a 50 yard zero will result in shots also being dead on at approximately 200 yards. What I like about the 50 yard zero is that your shots will never be off by more than about 3" from where you're aiming for any distance between 0 and approx. 250 yards.

Others advocate a 36 yard zero, a 25 yard zero and a 100 yard zero. It matters less which you choose than practicing and having some idea what your hold overs/unders are at different yardages.

And yes a 3x magnifier will make precision shots easier and will also help you better identify what you're potentially going to shoot.

 

[Metal god]

Im with Houndog 50/200 yard zero for me , love that zero for general use .

All guns are only accurate at two distance. First is when the bullet travels up through your point of aim ( POA ) and the distance it travels back down through your POA . You will have the same issue with the iron sights because the front sight base is so high of the bore axis . The great thing about red dots is they are parallax free from 50yds and beyond most of the time . This means you don’t have to place the red dot on the front sight post , as long as the red dot is visible through the tube it doesn’t necessarily need to be in the center as long as you’re shooting past 50 yards it will still have the correct point of impact POI . You can adjust your head to where the red dot is well above the front side post removing the front side post as something blocking your field of view through the red dot . You can however than lower your head and do what’s called co-witness the red dot and your sites and you’ll still be on target . I love me some red dots although I just bought a 3X prism scope that I’m kind of liking right now .

 

[bamaranger]

accurate

"Accurate at two distances"........I understand what is implied here, but the lingo does not seem quite right.

 

[jmr40]

All guns are only accurate at two distance.

He means zeroed.

All guns have 2 zeros. The 1st is when the bullet crosses line of sight while going up. And the 2nd time after it reaches the apex and crosses line of sight on the way down. How accurate it is at those ranges depends on a lot of factors.

Bullets on all rifles and handguns travel up in relation to line of sight when fired because the sights are above the bore. We naturally hold them so the muzzle is slightly higher than the breach. If the barrel were parallel to the ground bullets would start to drop as soon as they left the muzzle. The higher the sights above the barrel the more pronounced this is.

Most handguns are zeroed at the point where the bullet crosses line of sight while still going up. This will be 15-20 yards.

Not a fan of dot sights. I use low powered 1-4X or similar optics zeroed at 100 yards. On an AR the bullet will not be more than 1.5" above or below line my aiming point from the muzzle to around 200 yards.

Up close a scope set on 1X is every bit as fast to use as dot or iron sights. In fact, they work better in low light. And on 4X offer enough precision for shots well past 200 yards. They are only slightly bigger and with equal quality cost less.

 

[Metal god]

Lol , yeah zeroed sounds a lot better .

 

[jmhyer]

The problem with a LPVO on this particular setup is that it sounds like there's an A2 front sight/gas block. So the scope would need to be mounted high, which would present a similar dilemma as with the red dot.

 

[Metal god]

Yes front sight as well as parallax. I have both a 1x6 and a 3x and the blurry image inside 100yds is bothersome to me . Both are primary Arms so the circle and chevron make for easy acquisition but sight picture inside 100yds when using magnification is blurry .

All that said I like all my optics from red dots to full on high end scopes . They all however are on purpose built rifles . I put the 3x micro prism on my AR-10 which I think will be a nice home for that . A 1x4 or 6 would just add to much weight to an already heavy-ish rifle .

 

[bamaranger]

improvements

The decision regards a sighting device depends a bit on the intended role for the rifle. A simple 2-3 MOA dot works well for torso size targets or deer sized game to say 300 yds, at which point the dot will obscure the vital zone. If smaller targets are intended or more precision is required, a lone dot may not be the right choice for the rifle. I see the dot sight in more of a SD or fighting role, and the low powered variable (LPV)as better for general purpose work.

Rather than a magnifier, I think a LPV with some sort of illuminated reticle is far more practical and compact. I'm not a big fan of hanging a bunch of hardware on an AR, two devices to accomplish one task seems impractical.

I had a low powered variable on my AR carbine, , and ended up putting that scope on another rifle. Found a good price on a dot and installed it on the carbine as a replacement. With just a bit of use, I came to the conclusion that a LPV was a better choice for what I do with an AR, and have recently bought an illuminated LPV, returning to a scope and relegating the dot to the shelf.

Upgrades to an AR are a very broad topic, and keep an entire industry in business. If intended as a fighting rifle, you need some type of light, thus some type of mounting system, most easily accomplished by changing handguards with M-lok or similar rail arrangement. Some type of simple, practical sling, as you may need both hands for another task regardless of intended use, and grounding or propping the rifle is not always a solution.

My carbine has a terrible GI trigger, and I will change that some time in the future.

 

[stagpanther]

If you're using an unmagnified red dot and you have the fixed post on your barrel--generally speaking the front sight is going to loom in the field of view of your red dot, so you'll need to decide how important the co-witnessing of the dot to your sight is and then how you want it--in other words where the dot appears relative to the front sight and how much of the field of view the front post takes up. That should dictate what height you set the red dot at. It's really a matter of personal preference and your needs, I once had an Eotec and magnifier but for my kind of shooting eventually sold them, I'm not one for multiple gadgetry flip asides etc. and simply prefer the simplicity of a single fixed 3x prism optic. Different shooters have different intents/uses.

 

[taylorce1]

I use a Sig Romeo MSR 2 MOA red dot with Juliet 3X magnifier on my 7.5" .300 BLK pistol. I zeroed at 50 yards with Subs and I rock a 4" steel plate at 100 with 125 grain Supers. I like the MSR sight, and hardly use the magnifier. If I were using a 16" rifle I'd use a LPVO with either an illuminated reticle or 45⁰ offset holosight. My preference being an illuminated reticle.

 

[9x19]

For a self-defense rifle, I like this approach myself. The 36 yard zero.

https://www.youtube.com/watch?v=jttB1kUXfJE

 

[Willie Lowman]

Everyone seems to have missed that WTTGZ said he is using a 3.5 inch riser. That height over bore will give him a 50/300 yard zero. ...if he zeros at 50 that is.

 

[9x19]

I took that measurement as the length, vs the height of the riser...

 

[raimius]

It appears that the riser is a 0.6-1.0in adjustable height riser.
For the OP, how is the zero distance changing comfort? The difference between zeros will be VERY small fractions of an inch for the front sight. Your head should not move any noticeable amount.