3/13/11 - The ANGLESIGHT™ from Accutact is a dual-path optic that allows aiming and firing around obstacles and corners, while allowing the shooter to transition from a concealed shot to a standard shoulder-aimed shot without repositioning the optic on the weapon.

Background - Shooting round corners is not a new concept, and the benefits of being able to do so are obvious - you don't expose yourself from behind cover to your enemy. We've all seen movies in which bullets are ricocheted off different angles to strike a bad guy behind cover, but that's more fiction than fact, to try to figure out the angle at which a bullet will deflect off any given surface and actually hit a target. While it's not usually practical or accurate to try to hit a target by bouncing bullets off different surfaces like in the movies (I'm not discounting the fact that people get injured or killed by ricochets), it's entirely possible to hit a target accurately by using an offset sighting device that allows you to see and aim at a target that you do not have a direct line of sight with. Trick shooters have been doing this for a long time; using a mirror to shoot at a target behind them.

Some of you might have seen the German StG.44 used during WWII with the curved barrel attachment and mirror sighting device that allowed the StG.44 to be fired around corners without exposing the user to the enemy. This attachment actually changed the path of the bullet by 30° after it left the muzzle and traveled inside the curved extension. Another device is the Israeli Cornershot, to which a weapon is attached to a pivoting frame with an auxiliary stock and aimed via a video camera and monitor. It's not cheap, it's bulky, and is limited to certain weapons.

Much more compact and practical is the Aimpoint CEU (Concealed Engagement Unit) which is a periscope-like device which attaches behind a red dot scope, and enables the user to observe or engage threats from a protected position. However, it has to be removed (albeit quickly) in order for the user to direct sight through the red dot again and shoot from the shoulder.

The ANGLESIGHT from Accutact provides a dual sight path for the user, allowing sighting from 90° to the original line of sight and the original line of sight without having to remove or reposition the optic on the weapon. It's reminiscent of the M16 sighting device that clipped onto the old M16A1 carry handle, which was a tinted square of glass placed at an angle. It was used during marksmanship training and enabled the instructor to see the student's sight picture while the student was sighting on a target.

Description - The ANGLESIGHT consists of a dual-path optical cube enclosed in a glass fiber reinforced nylon housing, with open ports at the front, rear and one other side. The housing rotates about the line of sight axis in the circular ring mount, so that the side port can be pointed at any orientation around that axis (left side, right side, up, or any angle in-between). The mount is offered in three configurations: Standard (shown here), with a thumb screw, QR (Quick Release) and PLQR (Positive Lock Quick Release). The mount is compatible with any Picatinny rail and only takes up one cross-slot.

The heart of the ANGLESIGHT is the 1" optical cube, which is essentially a beamsplitter. A beamsplitter is a cube made up of two triangular prisms, glued together at the base. The base of one of the prisms is a half-silvered mirror, such that it allows light to be reflected (to the side port) and also transmitted (to the shooter). The beamsplitter itself is made of BK7 optical glass, which is a high quality borosilicate crown glass that's pretty durable and scratch resistant. I actually use both BK7 and Zerodur optical cubes at work, so I'm somewhat familiar with this. Beamsplitters are not cheap, and probably make up most of the cost of the ANGLESIGHT. The ANGLESIGHT is entirely optical, and does not require any zeroing, calibration or external power source.

Overall Features/Manufacturer Specifications

Optics - Dual Path, line of sight and 90º, BK7, AR coated
Magnification - X1
Eye relief - Unlimited
Weight - STD = 3.9 Oz.(110g) QR & PLQR=4.3Oz. (122g)
Dimensions - Length /width / height 1.8"x2.3"x2.75" (with mount)
Temperature Operational: -30ºC to 70 ºC
Storage: -39ºC to +100 ºC
Housing and mount Material - Nylon 6-6 with 60% Glass Fiber, Stainless Steel
Environmental - Water and fog proof (sand/dust)
Color/Finish - Black, non reflecting housing material
Mount - Picatinny rail mount (MIL-STD 1913)
Optical aperture - 1"x1" (24X24 mm)
Housing rotation 360 º
Compatibility - Works well with red dot/holographic sights, laser sights, iron sights, Tandem sight assemblies and NV sights

Installation - The ANGLESIGHT mount is designed to work with the 'standard'/'absolute co-witness' or the lower 1/3 co-witness height, depending on the optic, and the center of the rear port is a smidgen under 1.5" above the rail it's mounted to. So, to see if your optic is compatible, measure from the center of the optic window to the top of the rail and see whether it's close. The port opening is 0.95" tall, so you have almost a half inch from the center to work with. The ANGLESIGHT doesn't have to line up exactly with the optic, but the closer in height, the better. You can position the optic further forward to minimize the effect of an offset, as the further you place it from the ANGLESIGHT, the more the optic will be in the field of view.

In the photos below, I've positioned the ANGLESIGHT just behind the Insight MRDS and also the Aimpoint Micro T-1 in LaRue LT-751 Absolute Co-witness mount. Also shown is an Aimpoint Comp with lower 1/3 co-witness ADM mount, which also works just fine. The Comp has a larger tube than the T-1, so it's less sensitive to height differences. I pretty much get a full picture through the tube of the Comp.

I chose to mount the ANGLESIGHT as close to the optic as possible, although it's completely up to user preference. The standard thumb screw mount seems to hold pretty securely without loosening. While it's possible to use it with magnified optics, I don't think that it's an optimal use for it. First, the optic has to be mounted further forward to accommodate the ANGLESIGHT, while still ensuring that proper eye relief is maintained. Second, when viewing the optic through the side port, the eye relief still remains the same. So, if you scope has a 2" eye relief, your eye pretty much as to be within that when looking through the ANGLESIGHT's side port. It's only a mirror, after all.

The ANGLESIGHT can be mounted further back than I've illustrated; it's got enough clearance/height to overhang most back up rear sights.

The first application for the ANGLESIGHT is the most obvious; you can shoot around corners or obstacles from a position of cover or concealment, exposing yourself to the minimum. The second is training. With the ANGLESIGHT mounted on a weapon, the instructor can see exactly what the shooter sees, through the sight, and can aid or coach as needed. Of course, it's limited to mostly static positions as it'd be very difficult to follow the small port when someone is moving.

The third application is what came to my mind immediately (and got me excited) when I saw the ANGLESIGHT. I've tried mounting a small video camera on my rifle and helmet to get 'shooter's perspective' footage, and while it isn't bad, there's always a side offset from where the weapon is pointing. This is because of camera and mounting limitations - it's difficult to get it directly in line with the shooter's eye. The weapon is always pointing off to the side from the center of the picture. Even if you have a small tubular camera that you can mount on the weapon directly in line with the barrel, it usually gets in the way of aiming through the optic. With the ANGLESIGHT, it's now possible to mount a camera onto the weapon, looking from the side instead of facing to the front. The camera sees exactly what the shooter sees - a true 'first person shooter' perspective, through the sights. Also, this is the first time you can actually see a reticle or dot in the camera's picture.

I rigged up the mount below with my Flip Mino camera, using a VIO 6" flex mount and the head from a Ultra Clamp mount for positioning the camera. The flex mount is clamped in a LaRue Tactical MK31 pen flare QD mount. I haven't found anything else that works. I used this mount in my SCAR video, where the camera is mounted to the side rail and pointed at me in the latter part of the video.

Observations/Notes - The view through the ANGLESIGHT is darkened only slightly, and looks like a light tint. This is unavoidable and how a beamsplitter works. I've seen optics with more tint in their lenses than the ANGLESIGHT. From the user's perspective, the ANGLESIGHT doesn't get in the way of normal operation, nor does it change the way the red dot or holographic sight is used. You still keep both eyes open, put the dot on target and shoot.

When using the side window, you will obviously only see what's in the 1' x 1" window. The closer your eye is to the window, the wider your field of view is. Just like looking through a hole - the closer your eye is to the hole, the more you can see through it.

Since the ANGLESIGHT is a mirror, it works the exactly the same as if you were holding a flat mirror out and peering around a corner. The image is reversed in the mirror. What's actually on the left appears on the right, in the reflected image. This takes a bit of getting used to, and before the ANGLESIGHT is actually used, the user needs to spend some time training with it. The initial instinct is to move the weapon in the direction the target is moving in the image, to follow it. That will result in the weapon going in the opposite direction the target is moving. While the image is reversed, you still move the weapon in the direction you need to. So, if the target appears to the left of the dot in the reflected image, it's actually on the right, and the weapon needs to move to the right to engage it. If the target is moving to the left, it'll appear to move to the right in the image, but the weapon still needs to track left. It's obvious when you start using the ANGLESIGHT, but still takes some learning.

At the range, I mounted it behind the Insight MRDS and also an Aimpoint T-1, and didn't find it in the way when using either optic. It's in the field of view, but quite unobtrusive. Shooting with it around corners or barriers takes some getting used to, due to the reasons mentioned previously - the small field of view (which widens the closer you are to it) and the reversed image in the mirror. Once the target is acquired, you just have to pull the trigger. Another thing that helps is bracing against the barricade or corner so that the rifle doesn't jump around as much since it's not recoiling against the shoulder.

When observing a shooter's sight picture through the ANGLESIGHT, it's easiest when the shooter is in the prone position, as that's a pretty static position and the rifle won't be moving around much. Because of the narrow field of view, the observer needs to get relatively close to the ANGLESIGHT. This is of course, not advisable on the right side, in the path of ejecting cases. The observer/trainer needs to be well practiced with both the use of the ANGLESIGHT and how to interpret the sight picture so they can call shots properly (because of the reversed image). It can get a bit confusing to the untrained to call a shot to the lower left or right etc.

I was very excited to try out the Flip camera mounted as shown above, but was disappointed with the results (no fault of the ANGLESIGHT). The Flip camera is a pretty rudimentary camera, and the center of the picture was overexposed, due to the bright sunlit targets, and the automatic exposure reading the darker parts of the picture. It'd have worked better in overcast weather or against black targets in lower light. The MRDS dot was too light to show up against the targets on camera, so I swapped it out with the T-1, which has a brighter dot. Even so, the targets were just too washed out to see it. I took a few videos, but only one turned out decently, and it's only a few seconds. The short clip is shown below. I think that with the proper camera setup and lighting conditions, taking videos through the ANGLESIGHT has a lot of potential for getting some interesting footage.

Another thing to be aware of is the amount of light entering the port that you're not looking through. The ANGLESIGHT is a beamsplitter, and if there's more light coming in through the side port than the front while you're looking through the rear port, your view through the rear port can be 'overpowered' by the side port image. An example of this would be looking into a dark or shaded area though the rear port, and having bright sunlight illuminate whatever is to your side. The same applies when you're looking through the side port into a dark area, and the area to the rear port is very bright. It's not so much of an issue when using the rear port as you're keeping both eyes open and superimposing the dot on the target. The easiest solution is to rotate the ANGLESIGHT so that the side port faces down, towards the receiver under normal use. However, there's not much to be done when using the side port, except to be aware of it.

In summary, the ANGLESIGHT can be a very useful addition to a rifle with multiple uses (shooting around corners, training or video), as long as the end user is familiar with its use and practices with it.

12/22/11 - The Premium Diamond Sights from Diamondhead-USA, and available from Rainier Arms are a series of flip-up combat sights for the AR-15 which utilize proprietary diamond-shaped apertures and front housing, rather than the standard M4 round rear aperture with front 'wings' sight picture. They offer and alternative sight picture that is intended to make it easier to line up the front and rear sights.

Diamondhead sights - Diamondhead offers a variety of different sights for the AR-15 platform. They are:

• Premium Diamond Sights - diamond-shaped rear apertures and diamond-shaped front housing with a push-button locking mechanism
• Premium Hybrid Sights - diamond and classic (round) rear apertures and front housing with diamond-shaped outer housing and round inner profile, and a push-button locking mechanism
• Premium Classic Sights - round rear apertures and a round HK-style or M4-style front housing with push-button locking mechanism
• Premium "Auto-Ranger" Sight - with a proprietary 600 yd auto-ranging & bullet drop compensating system, with push-button locking mechanism
• Premium Gas Block Sights - increased height front sight for reduced height gas blocks
• SL Series Diamond Sights - features diamond-shaped rear apertures and front housing with a 'soft-locking' mechanism for rapid flip-up and push-down operation

All Diamondhead sights install with a clamping system using a flat head screwdriver to mil-std 1913 Picatinny rails, and have a standard A2 front sight post (except the Auto-Ranger front sight). The Diamondhead sights are made of mil-spec stainless steel and type 3 hard-anodized 6061 T6 aluminum. The shape of the base housing is less angular than the Troy sights, to which these look similar to, at first glance. A closer look reveals a difference in the clamp design, as well as a lower profile push button that doesn't stick out as far. Overall width is just about the same, though.

Having used a variety of AR15/M4 iron sights with the standard rear round aperture, the HK-style round front housing and the AR15 'winged' front sight, I was curious as to whether the diamond-shaped front and rear worked better than what I was used to.

From the Diamondhead website, the claim is that "The conventional round aperture makes shooting at longer distances difficult and inaccurate. Remember, rear sights are blurry during aiming. The simple fact is that it is easier for your eye to find the exact center of a blurry diamond than the exact center of a blurry circle. It is even easier and quicker for the eye to find the exact center of a Diamondhead™ rear sight’s aperture with the added posts at the corner of the diamond. These proprietary reference posts are unique to the Diamondhead™ sight and are not found on any other iron sight. The other main reason the Diamondhead™ (Pat.) diamond shaped aperture is better than a conventional round aperture is because round apertures don’t give you a truly ROUND picture of the front sight and target. The front sight tower of your rifle obscures the bottom portion of the conventional rear sight round aperture. This causes the the bottom part of the round aperture to be flattened – not round. The result is that it is hard for your eye to quickly make an accurate decision about how high up in this flattened circle is the exact center. The 3:00 o’clock and 9:00 o’clock corners of the Diamondhead™ aperture combined with the added accuracy of the reference posts, completely eliminate this problem."

Premium DIAMOND Flip-up Front Combat Sight - The Premium Diamond Flip-up Front Combat Sight has a standard square A2 front sight post that is adjustable for elevation. An adjustment tool is provided with each sight. The sight is about .540" when folded, and is kept folded by a detent. When mounted to a rail that's the same height as the receiver rail, the front sight is at the same height as the standard front sight. Deployment of the sight is accomplished simply by flipping it up. It locks in the up position and the release button on the left side of the sight is depressed to fold it back down. The difference between this sight and the standard one is the shape of the housing. It has a diamond-shaped profile that's open at the top. It's designed to be used with either a round or diamond-shaped rear aperture.

Premium DIAMOND Flip-up Rear Combat Sight - The Premium Diamond Flip-up Rear Combat Sight deploys and stows just like the front, and has the same type of release button on the left side. I measured it to be about .482" in height when folded down. There are two diamond-shaped same-plane apertures; a large one for 0-200m and a small one. Not only the hole in the aperture is diamond-shaped, but also the aperture itself. The apertures have 'reference posts' on the top and sides, which acts as references, further aiding in defining the corners of the diamond. One of the nice things about the aperture is that it's flat, and you can fold the sight down when either aperture is up, and pick either one as the default when you deploy the sight.

The aperture is protected on both sides by blades that have horizontal white lines on either side. Windage adjustments are made using a small coin, base of an empty case or flat head screwdriver. The positive click detents provide 1/2 MOA of windage adjustment with each click for the standard M4 sight radius. The actual value will differ if the sight radius is longer or shorter. Illustrated below are view through the large and small apertures, as well as the lower third co-witness through an Aimpoint T-1. Note that when shooting NTCH (nose to charging handle), the rear aperture is more blurry than the photos illustrate (human eye vs. camera's ability to focus etc). But you get a good idea of how it's supposed to line up.

The Diamondhead sights are shown mounted below. They have approximately the same envelope as the popular Troy sights, and are easy to deploy. and stow. The diamond shape of the front sight actually makes it easier to grab with gloves and flip up.

Premium Flip-up Front "Auto-Ranger" Combat Sight - Now this is something different. It's the 'Auto-Ranger' Combat sight with AR-BDC (Auto-Ranging Bullet Drop Compensating) front sight system. This also has the diamond-shaped housing, and push-button lock, but it also has the ability to quick-range your target and dial in the front sight height to hit at pre-set distances. Instead of the standard single front sight post that you zero at a particular distance, then use the rear to adjust for the different ranges, the Auto-Ranger has a 'wheel' with five different height posts. A knob on the left side is marked 0-2, 3, 4, 5 and 6 (for 100's of yards). To estimate range, you rotate the knob until you find the post that matches the size of your target, which is a standing man. Then you just shoot.

Initial zeroing is done by rotating the small dial at the base of the sight tower - this raises and lowers the whole wheel assembly. Rotating it to the right raises point of impact.

It's zero'd as you would a standard A2 front sight. The Diamondhead literature doesn't state whether the AR-BDC is calibrated for 55 or 62 gr ammunition, so I'm assuming it's 62 gr . Since it says "Automatically estimates distances of man size targets and adjusts for bullet drop for M4 5.56 ballistics to 600 yards.", I can only assume that it means that the BDC is correct for a standard 14.5" barrel with M4 sight radius. This info should have been readily available in the packaging or on the website, but I was unable to find it, and DiamondHead never responded to my email inquiry. It's important, since a BDC only works with a particular trajectory. Diamondhead needs to put the bullet weight, barrel length, velocity, recommended zero distance, and sight radius that the Auto-Ranger sight is designed to be used with, at the very least. Of course, it's also the responsibility of the buyer to confirm his own weapon at the different distances.

The Auto-Ranger sight can be used in conjunction with a diamond-shaped rear aperture, or standard round one. The Auto-Ranger is more bulky than the standard front sight, with the knob on its side and increased height on the rail. It measures about 0.77" above the rail when folded down.

Notes/Observations - I'll be honest; I have not done a lot of iron sight shooting on my ARs lately - I've been using red dot sights almost exclusively. I use the irons when I'm sighting them in, and occasionally during drills so I don't completely forget how to use them. While there are a lot of people who can shoot irons accurately out to 600 yards, I'm not one of them. My less-than-stellar (bad) eyesight, and inability to see a target at longer distances while focusing on the front sight makes irons much slower for me. I have friends that can see 5.56 holes in paper at 25 yards with their naked eyes. I can't, even with corrected vision.

My limited experience with irons on the AR platform started with the standard M4 and M16 A2 sight pictures, which everyone should be familiar with. This is basically the same sight picture as the M14 or M1 Garand, or FAL, with which you use the blades/wings to align the front sight consistently with the rear aperture. Being honest again, while this obviously has worked well for a lot of folks over decades, I don't find it very natural to align. I know what my sight picture is supposed to be, and am able to get it pretty consistently, but it's not as intuitive (visually) as aligning same-shaped front and rears, for me. I've also used the HK diopter sights, with which you align the front circlular hood in the rear aperture, as well as the rounded front Troy sights with the open circle. I find these easier to align than the standard sight picture, although I don't like the way the HK front sight is closed on top.

The arguments I've heard against using a circular front sight hood with an adjustable post is that the tendency is to center the target in the circle, rather than place it right on top of the front sight post. I don't seem to have that issue, and while I always center the front and rear circles with each other, I always place the target on top of the front sight post, no matter whether it's lower or higher relative to the circle. Following that, I had no issues using the diamond-shaped apertures on the Diamondhead sights either, even if the front sight post isn't perfectly centered in the front sight hood.

I did not have a chance to shoot the Auto-Ranging front sight at distance to see whether the AR-BDC works, so I've included it here for information only. I did sight on various object at different distances just to get a feel for using it, and my eyesight just isn't good enough to keep a front sight in focus and hold it on a blurry man-sized target at 600 yds. When I focus on the front sight, I pretty much lose the target if it's not contrasted well against the background. One thing that I feel might improve the Auto-Ranging front sight is to make each post slightly narrower for each increasing distance.

I did shoot irons-only at a recent range session at distances from 5 to 50 yards, during various drills. I also compared them to a set of circular aperture sights. I do find the Diamondhead apertures more natural to align than the standard sight picture. When I first got them, I thought that the cross-shaped reference posts were useless, until I actually found that they do help, even though the rear aperture is blurry. The side white markings on the rear blades I found unnecessary, though. My eye centers the front diamond in the rear readily, as you automatically try to equalize the white space between the two. The vertical and horizontal corners also aid in lining them up correctly. Throughout all the drills, I had no issues placing the front sight post right on target, vs. centering the target in the front diamond.

Now, whether or not the diamond-shaped aperture is faster to use than a circular front and rear, I'm undecided. I've tried numerous presentations with the diamond-shaped sights and circular front and rear, and I don't notice a difference in speed or ease. The diamondhead reference posts might help a bit more by making it more noticeable when there's a misalignment, but the difference to me was undetectable. Diamondhead mentions the flattened circular sight picture as a detriment when using circular front sight hoods, but my eye doesn't try to use the top or bottom of the circular hood - it looks at the white space between the front and rear circles as a WHOLE, at the 10:30, 2:30, 5:00 and 7:00 positions, and I don't have an issue detecting whether they needs to move up or down relative to each other. I found that the greatest amount of time spent (in the big picture) was changing my focus from the target to the front sight. That's what I have most difficulty with, I've found, as I grow older - getting a clear front sight focus; whether it's with a rifle or pistol. That's why for me, a red dot is much easier to use under all circumstances than iron sights. But this isn't about irons vs. red dot.

My conclusion with the Diamondhead sights is that they're well made and offer the same features (and more) as the other better-made BUIS on the market today. While the diamond-shaped aperture works better for me than the standard sight picture, I don't really notice a difference in ease or speed when compared to a circular front sight; but they're definitely not slower or harder to pick up. Since we all have different eyesight, others may notice more of a difference than I did, and may see more benefit. For me at least, I prefer them to the standard sight picture.