One major advantage of the AR platform is the ability to easily and reliably mount optics. Another chief advantage of the AR platform is SAWC. If we are concerned with the SAWC of the gun, that doesn't go out the window when we consider optics. There are many optics manufactures that produce extremely high quality optics, but are too heavy for what they provide. (Nightforce and US Optics are two prime examples.) If you find an optic worthy of their name, but they managed to make it a reasonable weight, go for it! But, remember, every ounce counts.
The thinking in favor of using these extremely heavy optics is maximum dependability - like if you were fighting in Iraq or Syria, jumping out of Helos, jumping in and out of APCs, etc. First off, very few people who are buying their own optics are actually doing those things with their own optics. Secondly, how much more dependable or durable are these heavier optics than, say, a Vortex or a Burris? I mean, if you shoot it or run over it with a tank, the brand, quality, and weight really doesn't matter. The best way to determine durability for real-world use is, if you drop the gun and it lands on the optic, will the optic still work and did it hold zero? Based on that definition there are numerous manufactures that fit the bill. Of those manufacturers, who has the best warranty? For my scopes, it seems to always come down to products by a handful of manufacturers, notably including: Vortex Leupold, and Burris. For Red Dots, obviously the aforementioned manufacturers also make the cut, but I would add Aimpoint and Trijicon.
So, what specific optics do I recommend for an AR15? Well, I tend to break those down into 2 categories based on cost: is it either more or less than $500, basically. If you're outfitting multiple guns and have middle-class income, paying more than $500 is a lot to ask. If you're only going to outfit 1 or 2 guns and you want the very best available, something above $500 might be possible. "Buy once, cry once," as they say. If you're going to pay over $500 of your hard-earned money for an optic, it better be extremely durable and have valuable features you can't find on lower-priced optics. Then, I sub-divide those categories by Red Dots (Typically zero magnification) and Scopes (Magnified). Which one you need depends on POU and you may possibly need both. I will note which Red Dots I would advise as the primary optic and which ones will be best used as a secondary to the scope.
So, really, what do I recommend? Bear in mind that this is for an AR15, chambered in 5.56, not a Georgia Precision rifle in 300 Win Mag, so these are not meant for extreme long-range. Here's the list, which I plan to update periodically for new products and changes to products:
- Red Dots
- Vortex SPARC II - Tough Red Dot (Shockproof, waterproof, fogproof) that weighs 5.9 oz in a compact size. This isn't the best Red Dot money can buy, but it has Vortex's VIP warranty and a pricepoint at $200. The battery lasts a long time (not like Aimpoint, but really good), it has both an automatic shut off set at 12 hours (not so short it cuts off while you're shooting) and an on/off button to be sure you aren't wasting battery life. I also like the temperature range of this optic. Some brands have poor operational temperature range, like Holosun, but this will work in most environments.And, it exactly co-witnesses with iron sights.
- Burris AR-F3 - This is a small, lightweight option that is designed to co-witness your iron sights. At 4.6 oz, it's one of the lightest weight options available at a very reasonable price. The 3 MOA dot is a little large for my taste, but for bumps in the night, this is great for fast target acquisition. The overall design does a good job of not cluttering your field of view. This also has the definitive push-button on/off selector that I require - I need it to turn on when I tell it to and I need it to stay on, regardless of light conditions. And, I like the peace of mind, knowing that it is actually off before I put it away.
- Aimpoint Pro -A little heavy for a Red Dot, coming in at 11.6 oz, but it's super durable and it's not any heavier than your typical scope. You also get the benefit of up to 30,000 hours of continuous use - that's some battery efficiency there. (Compare to 5,000 hours for the Vortex SPARC II.) This also has an operational temperature range that is beyond outstanding - by far the best range of the budget Red Dots. All that is good considering this is pretty close to the $500 limit. In fact, you can buy two SPARC II sights and some extra batteries for the same price. The good thing about this is the ultra-dependability of these sights - if you want the very best so that you can bet your life on it, even though you're on a budget, you're getting the premium dependability for a reasonable price with this optic. So, would I recommend this over the other Red Dots? If I were in Iraq or Alaska, I'd prefer this Red Dot due to operational temperatures. In most of the US, I would be just fine with the AR-F3 or the SPARC II, plus I'd save weight and money. I think it's great to have at least one of these Aimpoint sights, but it's not needed for self-defense in most areas.
- Vortex Venom - The Venom is all of 1.1 oz! That is incredible. It's also waterproof, shockproof, and fogproof. So, what is a "secondary" red dot? If your primary optic is a scope, this is a great 45 degree offset option for close-range because of the weight and size. This will help when you are transitioning between close and long-range targets. (For instance, the red dot can have a 25 yd zero, while you zero your scope at 100 yards for distance shooting.) This could be a primary red dot as well, but Vortex does not make an exact co-witness mount for this. If you're ok with a 1/3 co-witness with your irons and want the lightest weight possible, this is a good choice for that as well. (I prefer that my red dot and my irons verify each other - it's helps my distance shooting with a red dot to be able to line up the front sight and the red dot through the rear aperture.)
- Burris FastFire 2 - Basically, this is the Burris competition for the Venom. This is very similar to the AR-F3, but without the co-witness mount. You should still be able to co-witness this optic if you want, but it is intended to be used on top of the scope mount or on a 45 degree offset for a secondary optic. I prefer the Venom due to weight and dot size, but have no issue with this for CQB uses. It's a great option with a great warranty. If you're more familiar with Burris or prefer a larger dot, this is for you.
- Vortex Diamondback 3-9x40 - Shockproof? Check. Waterproof? Check. Fogproof? Check. Check. It has excellent glass for the price and it is only 14" and 11oz. Such a good scope for the money and the warranty is outstanding - it is hard to find a better value. The biggest drawback is that it is Second Focal Plane - which means the reticle's marked adjustments are only accurate at the highest magnification. However, for fast adjustments to point of aim, doing a hold-over with the Dead-Hold BDC Reticle is easy.
- Note: If you're shooting beyond 50 yards, Ballistic-Dot Reticles give a quick point of reference to adjust your aim for longer distances. I would prefer a simple MOA grid reticle for precision, but that costs more money. The problem with Ballistic Dot reticles is that each load and barrel length has a different velocity and, therefore; a different trajectory. So, it's unlikely to get a reticle that matches your specific load/gun. Now, you can adjust the ballistic dots on many of these reticles, but then you shoot another type/load of ammo and the holdovers are off again. However, when you have a split second to take a shot, these are much faster than turning knobs and more accurate than just guessing because it gives a point of reference. If you need precise MOA adjustments, the turrets will provide that for you.
- Red Dots
- Trijicon MRO - These are all the rage. They might also fall into the under $500 category if you get them on sale. At 4.1 oz, it's very light. a 2 MOA dot is also a nice. (I prefer 1 MOA dot size, but this is still excellent, especially for CQB.) Of course, it's shockproof, waterproof, fogproof, and extremely capable of long-term use - a hallmark of Trijicon products. The battery will also work for 5 years of continuous use. Yeah, you don't even need to turn it off - you'd have to replace the battery every 10 years if you were storing it on a shelf, but this provides 5 years of continuous use. That is mind-blowing. It also uses 7075 T6 aluminum - which is stronger and harder than the typical 6061 aluminum that is used in sights and scopes. If you're willing to spend a little more, this is a truly excellent sight.
- Aimpoint Micro T-1 - 3 oz and a 5 year of continuous use battery life. Shockproof, waterproof, and fogproof. You can also use this as a primary and, frankly, this is the best red dot money can buy, IMO. (I prefer these over the T-2, actually.) Usable in temperatures ranging from -45°C and +71°C. The weight, battery life, temperature range, and dependability make this an awesome choice, especially for set ups where this is the primary (only) optic. The problem: they aren't cheap. As a secondary optic, they're a little heavy, but they still have great benefits, like a mind-blowing 5 years of continuous use for the battery. You may not need this good of a secondary optic (if you even need a secondary optic at all), but anyone who has one should use it with extreme confidence.
- Trijicon RMR - This is a rich man's Vortex Venom. Why spend the extra money? 4 years of continuous use battery life and the company reputation. Is that worth it? I don't know, but I would rather not spend $600 on a secondary red dot. If money was no object, I'd consider this solely based on the battery life because optic batteries are the kind of thing that can get you killed when they fail you. Between this and the Aimpoint Micro T-1, I'd prefer this as a secondary optic due to weight, but the Micro is more versatile (For use as a primary) and more technically impressive. I won't own any of these because I view the Venom as a reasonable alternative at a much lower price point. But, if you have one, the RMR is more premium in terms of precision adjustments and having a more precise 1 MOA dot. In my experience, these are preferred by competition pistol shooters because of the added accuracy potential of the 1 MOA dot and the precision measured optic.
- Burris XTR II 2-10x42 - First, it's extremely heavy-duty, but a reasonable 22.7 oz with a 13.5" length. Secondly, it's First Focal Plane, which means the markings on the reticle are accurate no matter what magnification you're using. The key difference in price of scopes is the glass - not just quality, but the reticles offered. In this case, I love the SCR-MOA reticle. I prefer MOA, so this is a great reticle for me. The ability to use this reticle for a precise holdover, instead of turning knobs, is such an advantage. And, another key advantage (which should really be standard on all scopes) is that the turrets and the reticle match eachother! (They both use MOA in this case.) So many scopes have MOA turrets with a Mil-Dot reticle, which is completely retarded. (A prime example of gun products being made by people who don't shoot.)
- Note: I don't have an issue with Mil-Dot, it's just not my preference. I just won't waste my money on a scope that makes me convert from one to the other. There are great Mil-Dot reticles out there, just be sure to get one with a scope that has Mil-Dot turrets.