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Hand holding a Gideon Optics Advocate on a Gideon Optics tool mat

Mounting a 1X Prism Optic to an AR-15

Shoot better with your semi-automatic rifle or carbine by adding a 1X prism AR-15 scope to your gun. The AR-15 scope mount process is a quick, beginner-friendly customization that’s ready for the range in minutes so you can get out of your workshop and start zeroing in your new performance optic. The Advocate 1X Prism scope comes with everything you need for installation on a 1913 Picatinny rail or industry-standard T1/T2 mounting location. It’s an easy, cost-effective way to upgrade any AR’s sight picture.

The Advocate: A True 1X Prism 

The Advocate is a 1X prism scope, which means it’s a type of red dot sight that uses prismatic lenses to overlay a bright, illuminated reticle on an etched reticle. The use of a prism gives you a sharper image, even if you have astigmatism, and moves the apparent positioning of the reticle farther forward toward the target. When you use a prism optic as your AR-15 scope, you get lightning-fast target acquisition, more intuitive aiming, and more precise shot placement. Prism scopes can also be used in conjunction with iron sights if aligned for co-witnessing or with magnification optics for longer-range shooting.

Straight Out of the Box

The Advocate comes pre-mounted on a canted 1913 Picatinny riser. You’ll also find a fresh CR-2032 battery, a cleaning cloth, the owner’s manual, and a pair of wrenches for installation. The lug screws on the riser already have blue threadlocker on them. However, if this is a re-installation, you may want to have a bottle handy when mounting your AR-15 scope.

Installing Your Advocate Prism Scope   

Make sure you have a clear workspace, the tools, and the time to tackle this job. Luckily, due to the split-receiver design of the AR-15, a small work table, around 20 minutes, and the included wrenches should have you covered under most circumstances.

  1. To Reverse or Not to Reverse
Gideon Optics Advocate out of the box

Out of the box, Advocate is mounted on the riser in a reverse cant position, meaning the riser slants back toward the eye-piece. If you prefer a forward cant that positions your AR-15 scope as far forward as possible, you can easily reconfigure the AR-15 scope mount for a forward cant. On the underside of the riser, remove the four mounting screws that secure the Advocate. 



Once removed, you’ll see a standard symmetrical Aimpoint T1/T2 mount footprint that lets you reverse the riser position and resecure the optic with the same four screws. This mount footprint also lets you attach the advocate directly to a T1/T2 mount. Please note: there is a fifth screw on the underside of the advocate that should never be loosened, as it is used only for the nitrogen purging process at the factory.

  1. Prepare Your Firearm

Make sure your weapon is unloaded before beginning any work on your AR-15. Remove the upper receiver to make mounting easier if you have limited elbow room. Now is a great time to spot-clean your top rail to ensure no grit, grime, or moisture is trapped under the AR-15 scope mount.

  1. Prepare Your Optic

Read the owner’s manual that came with your optic to ensure you know the basics of using the Advocate. Install the included CR-2032 battery in your Advocate and switch it on. Look through the eyepiece and verify illumination, cycle through some brightness settings, and then turn off your optic. Loosen the lug screws on the rail mount, and you’re ready to get started.

  1. Mount Up!

Slide the mount onto your rail. If you intend to use a magnification scope in conjunction with the advocate, remember to move your AR-15 scope placement farther forward to allow space for both optics. Position your Advocate and tighten the screws on the AR-15 scope mount, pushing gently but firmly toward the muzzle. This forward pressure reduces wiggle and better positions your optic to resist movement caused by recoil.

  1. Bore Sighting Your AR-15 Scope

Bore sighting your scope for 50/200-yard battlesight zero accuracy is easy. Remove your lower receiver and the bolt carrier group. Sight downrange through the bore of your rifle at a 50-yard target. While holding the upper steady, look through your AR-15 scope at the tip of your etched or illuminated reticle. This point is where the Advocate is aiming, which will likely not be on the same point as you sighted through your bore. You want to eliminate as much deviation as possible between the two so that zeroing the weapon with live rounds is a shorter, less expensive process.

  1. Adjusting Windage and Elevation 

 Both windage and elevation are adjustable on the advocate at 1 MOA per click or about one inch at 100 yards, which means at 50 yards, each click is ½ inch of movement. Your windage and elevation dials are marked to adjust the point of impact with live fire. For bore sighting, you’ll reverse the direction to bring your optic closer to the bore sighting. Estimate the inches your reticle is deviating from your bore-sighted aiming point, and make the needed adjustments. For example, a reticle about three inches right from the bore-sighted point will need six clicks to the right to bring it closer. Remember, bore sighting is not for zeroing the weapon–it’s to get your initial rounds on the paper.

  1. Zeroing Your AR-15 Scope
Mike from Gideon Optics zeroing the Advocate prism scope

Once you’ve got your bore and optic sighting close together, reassemble your firearm and get ready to zero the weapon. When the range is hot, aim and fire three rounds at your target. Measure the deviation and adjust your windage and elevation. Since we’re using live ammo that provides a point of impact, do not reverse the direction of your adjustments as you did with bore sighting. An impact point three inches to the right from your bore-sighted point will need six clicks to the left to move the point of impact closer to zero.

  1. Take Your Time

Avoid making large adjustments while zeroing your weapon to avoid overcorrection. It’s far too easy to spend all day making dramatic adjustments that send shots all over the paper (or off it). Small, incremental adjustments will get you closer to zero each time without overshooting (pun intended) your mark.

Mount an AR-15 Scope You Can Count On

The Advocate is a reliable 1X Prism scope that’s built for practical everyday use, has the features you need, and is priced to leave you more money for more shooting. Sign up for our email list to get notifications about new product launches or special pricing. Order your AR-15 scope from Gideon Optics today.

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