Shooting from CQB distances out to 200 meters and beyond can greatly be aided with the use of red-dot or holographic electronic optics. They are much easier to shoot with than traditional iron sights.
When adding a red-dot or holographic optic you will want to:
- Choose the best optic for your needs.
- Install your electronic optic onto your rifle and add backup sights just in case your electronic optic fails. (Don’t forget to use Loctite thread locker on all the screws.)
- Choose the best “battle sight zero” for your rifle, and then zero it at the range.
- Co-witness the backup sights with the reticle of the electronic sight.
- Carry spare batteries with the rifle.
Flat-Top AR15 Rifles With Removable Carry Handles:
Most AR15 style rifles built in the past ten to fifteen years do not have a built in carry handle / rear sight assembly, but rather a “Picatinny rail” that allows the user to have a choice as to mount holographic sights, red-dot sights, magnified optics, simple rear sights, or even a removable carry handle / rear sight assembly. These are referred to as “flat top” rifles. In the past, anyone wanting to mount optics on top of their AR-15 style rifles were forced to use some type of adaptor to mount their optics on top of the fixed carry handle. This set the optics too high to take advantage of the 5.56x45mm NATO rounds fairly flat trajectory, and it set the optic too high for the shooter to get a good cheek weld on the stock. The flat-top design allows you to mount your optics so that the aiming reticle is the same height above bore as the tradition fixed “iron sights”.
Some flat top rifles are sold with a removable carry handle that looks exactly like the older fixed carry handles, except that they can be easily removed with two knobs. Some rifles are sold without the carry handle as manufactures realize that most end users will want to remove them to customize their rifles with optics and accessories. If you choose to simply use the carry handle then don’t mount any optics to the top of it. This defeats the purpose of the removable carry handle. Remove it and mount the optics to the rifle’s rail.
Red-Dot Sights and Holographic Sights:
Savannah Arsenal’s Tactical Rifle Optics Page
More details on the subject of red-dot and holographic sights can be found on the linked page above, but without being repetitive with the other page I would highly recommend the Aimpoint “PRO” (Patrol Rifle Optic) red-dot sight (pictured right), or the Eotech’s 512 holographic sight. Both are high quality optics that are purpose built for AR15 style rifles and are the correct height to co-witness with backup sights (discussed further in the article).
Always keep spare batteries for the optic with the rifle. I really like Magpul’s MOE grips (pictured right) as they have a compartment where you can store spare batteries for your optic or weapons light. I place the battery in a small plastic arts & crafts “crack bag” before storing it in the grip. (If you replace your grips, be very careful as there is a very small spring and pin that may fall out when you remove the original grip. Be careful not to damage the spring when installing the new grip. Be sure to add a dot of Loctite to the screw that holds the grip to the rifle’s receiver.)
Be sure to add a Backup Iron Sight (discussed next) as batteries can go dead and electronics can fail or be destroyed. With backup sights you will be able to stay in the fight.
Backup Iron Sights (BUIS):
BUIS is an acronym for “backup iron sights”. This is nothing more than a catchy label for backup sights that you can use when and if your primary electronic or magnified optic is damaged or fails. “Iron” simply refers to their metal parts to differentiate them from electronic optics, although none of them are made from iron, but rather aluminum, steel, and plastic. Backup sights can simply be a rear sight that sits on a flat-top receiver behind the optic, or it may be a set of both front and rear sights for an ORC (Optic Ready Carbine: a carbine with only rails on top and no front sight base that is ready for customization by the end user).
If you run some type of aiming device (holographic sight, red-dot sight, or magnified optic) on your rifle then you need to have a backup sight(s) on your rifle. Murphy’s Law dictates that your electronic optics will break or be damage, your scopes will break or fog up, and your batteries will go dead at the worst time. If this happens and you don’t have a backup system for aiming, then that weapon is out of the fight. You soon will be too.
One day, after making a long drive to the range to shoot my M4, I discovered that my Eotech’s batteries were dead. Although I was ashamed for not having an extra set of batteries with my rifle or in my range bag, I was still able to utilize the rifle’s backup sights and enjoy a long morning of shooting. Fast forward to the present: Besides installing backup sights on all of my rifles, I store an extra set of batteries in each rifle’s Magpul MOE aftermarket pistol grips, and keep extra batteries in my range bag.
Stay away from cheap Chinese made “Airsoft” quality parts and gear, such as Aim Sports, Promag, Leepers, UTG or NcStar. Save your money and buy quality gear. Your life may depend on it. As always, when you install any parts, be sure to use Loctite thread locker on the threads of the screws to keep your parts from loosening up when you shoot.
Manufactures of Quality Backup Sights include:
If you are going to install backup sights on a Bushmaster brand carbine, be sure to read:
Backup Sights on Bushmaster Brand Carbine With Removable Carry Handle
What Distance to Zero Non-Magnified Optics & Sights:
Battle Sight Zero:
Simply defined, “Battle Sight Zero” is a theoretical “set it and forget it” setting for your iron sights or non-magnified optics. You will want your sights set at a distance that will provide the flattest trajectory, and thus the least deviation in point-of-aim and point-of-impact at varying distances. Fortunately for those using .223 Remington / 5.56mm NATO rifles, there is a distance that you can zero your rifle and enjoy a very flat trajectory out past 200 yards away.
Find The Flattest Trajectory:
It is important to zero the elevation of the sights with a single setting that will take the most advantage of the flat shooting trajectory of the 5.56mm/.223 caliber rifle round. The following graphs compare the trajectories of bullets when zeroed at 25, 50, and 100 yards.
100 Yard Trajectory:
The first chart shows the trajectory of a 5.56mm NATO round when fired from an AR15 style rifle. The dash line represents the shooters point of aim. The bullet departs the barrel approximately 2.5″ below the point of aim. It’s flight path reaches the shooters aiming point at 100 yards (point-of-aim (POA) = point-of-impact (POI). The bullet then drops back down to 2.5″ below POA at 200 yards, and plummets drastically after that. This isn’t a terrible zero if you never plan on shooting past 200 yards as the bullet will impact somewhere within the distance of the barrel to the top of the rifle’s sight base. Not terrible, but you can do better.
25 / 300 Meter Trajectory:
The next graph represents the traditional military method of zeroing the rifle at 25 / 300 meters (meaning that you zero the rifle at 25 meters and can expect POA = POI at 300 meters). This was traditionally done with adjustable rear sights, such as those found on rifle’s equipped with carry handles, set on the 300 meter setting, but the target set 25 meters away. This is a TERRIBLE zero setting. At 100 meters (91 yards) the your rounds will impact over 4″ above your POA. At 175 meters the bullet impact will reach its peak apogy at roughly 6″ above your POA. The USMC has finally accepted that this isn’t the most efficient way to zero an AR15 / M16 style rifle. Do not use a 25 meter “set it and forget it” zero.
50 Yard Zero:
The next graph illustrates the ballistic trajectory of a 5.56mm NATO round with a 50 yard zero. This zero is commonly referred to as “Improved Battle Sight Zero”. As with the graphs above, you can see that the bullet leaves the rifle 2.5″ below the point-of-aim (POA). The bullets trajectory will pass through the shooters point-of-aim at 50 yards. At 100 yards it impact approximately 1.5″ high. It will reach its peak apogy of 1.8″ at approximately 140 yards. Around 220 yards the round will again pass through the shooters (POA). At 250 yards the round will impact approximately 2.5″ below POA. This data shows that on its flight from the rifle’s muzzle out to 250 yards, the bullet will hit somewhere within plus or minus the height of the rifles front sight base (+/- 2.5″). That’s pretty darn flat.
Recommendation:
The final graph compares all three trajectories. The 100 yard zero isn’t terrible, but you can do better. The 25 / 300 meter zero is terrible. The 50 yard zero will provide the combat shooter with the flattest trajectory out to approximately 250 yards, and is the recommended distance to zero your iron sights and non-magnified optics as a “set it and forget it” Battle Sight Zero setting.
Battle Sight Zero For Red-Dot and Holographic Optics:
Simply zero your rifle for point of sight / point of impact at 50 yards. Make adjustments until bullet impact is right on the red dot. For shots at 300 meters simply hold over approximately one dot.
As discussed earlier, if you are going to install any type of electronic aiming device, it would be prudent to install some type of backup sights. You will also want the backup sights to be zeroed at 50 yards. With the optic and the backup sights properly installed and zeroed, it will look like the aiming dot of the optic is bisected by the top of the front sight post. The sights and optic will then be considered “co-witnessed”.
Co-Witness Iron Sights and Optics:
Weaponevolution.com’s Guide To Understanding Co-Witness
The easiest way to co-witness your optic and backup sights will be to carefully zero your optic first on the range so that your bullets are hitting exactly where you aim at 50 yards. You want to zero your optic first because it can be more finely adjusted than most backup sights. Next you will zero your backup sights. If your optic is correctly zeroed then you won’t have to fire a single shot to zero your backup sights. With the majority of backup sight you can not adjust the elevation of the rear sight. You must use a front sight post adjustment tool to raise or lower the front sight until it appears, when you are looking through the front and rear backup sight, that the optic’s reticle is horizontally bisected by the tip of the front sight post.
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