Optics and Accessories Page 3

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IO Cover - Aimpoint Micro Lens Caps

9/28/12 - The IO Cover is a one-handed, built-in lens cap for the Aimpoint Micro series of optics, providing protection for the lenses from rain or sand. They open, close and stow with one hand. The catch? They're not in production yet. So this is a preview to help spread the word on the project.

Background - The Micro has proven itself to be an extremely durable and capable optic, but lacks the flip-open lens covers that its big brothers, the Comp series, has. While some may argue that lens covers aren't needed, I feel that it's a good idea to be able to protect lenses when not in use, against the elements and damage. The cleaner and clearer the lenses, the better the device is able to be used to aim. While occlusion of the front lens does not pose a serious issue (as the optic can be used as an occluded eye gunsight (OEG) provided any difference in POA/POI is known when using it as such), occlusion of the rear lens can render the sight useless for obvious reasons. Mud, snow, frost, sand, dust, water etc. on the rear lens can either block the view through it completely, partially, or distort the view of the dot.

The rubber bikini covers that the Aimpoint Micro T1/H1 optic is provided with has always left something to be desired. Since it's not affixed to the Micro, it can get lost; plus it's not the most convenient to retain on the weapon when the lenses are uncovered. Removing the cover by ripping it off is fast, but then it's off the weapon. Replacing it isn't the quickest task either, when it's stored around the base of the optic.

I've seen the question come up ever since the Aimpoint Micros hit the market: "Anyone figure out how to put flip-open lens caps on it?" The first alternative looked at is usually Butler Creek-style lens covers. However, the Micro doesn't have enough of a shoulder at the rear to accommodate a slip-on lens cover. The rear lens is the one that's facing up more of the time, as the rifle is pointed down when it's being carried, more often than not. GG&G came up with their Accucam QD mount with integral scope covers, but it adds too much weight and bulk, in my humble opinion, plus you're stuck with their mount.

While many people thought about designing and making some lightweight lens caps for the Micro, only now has someone taken the steps to design and prototype a cover. The next step is to put it onto production and this is where your involvement is needed.

Development - The concept started in Joe Chen's head about three years ago. The idea came to him in a carbine class during the rain - he was using his hand to cover up his optic. With his engineering and design background, it was only natural that Joe set upon coming up with a solution.

Development of the IO Cover included trying out all sorts of configurations and options. Ever since Joe went public with the project, he's received an enormous amount of feedback and suggestions. A lot of which he has already considered while developing the IO Cover, and some that he has not, but takes into account. While you can design something forever, and try to satisfy everyone's different needs, there comes a point where the design has to be fixed, and produced, then after some time, revised as necessary. That's where this project is - the prototye shown here is actually Revision 5, and will likely be the initial production model.

The next thing was to figure out how to get the IO Cover manufactured. Joe approached a lot of people in industry. While many were interested, no one stepped up to help fund the project. While seemingly simple, a mold for a part like this is expensive; $20,000 is needed to pay for the tooling and initial production run. Joe decided to use Kickstarter to get this project off the ground. The material has been carefully selected for durability, cut/tear resistance, chemical resistance, heat/cold characteristics, etc. Overall, Joe has evaluated at 3 different manufacturing processes, 10+ materials, and a handful of vendors for their ability to deliver quality on schedule. This project will only be funded if at least $20,000 is pledged by Monday Oct 22, so there's a time factor involved.

Kickstarter - I had actually never heard of Kickstarter before this. Kickstarter is a funding platform for creative projects, and depends on the support of others to fund a project. Read more about it here. People can pledge at different levels, with each level offering different returns.

Description - The IO Cover builds the lens caps into a protective optic cover for the Aimpoint Micro. It's going to be made of an elastomeric polymer, and can be molded in different colours. It looks similar to the out rubber cover that Aimpoint offers for the M-series optics; except that it has front and rear lens caps attached to it. The main body of the protective cover acts as a base to attach lens caps with flexible living hinges. The IO Cover wasn't designed originally as a protective cover; the protection of the body is just a by-product of the necessity for something to attach the covers to. Icing on the cake, so to speak.

The front of the Micro optic has a lip for the front lens cap to grab onto in the closed position. The rear lens cap is a different story. There’s literally nothing on the rear of the optic that can be used to keep the lens cap closed. Joe tried a number of approaches including latches, steps and detents, but none of them would keep the lens cap closed. The solution was to extend the rear of the protective cover just enough to form a ridged lip that the lens cap can snap onto. It took 2 years and 4 revisions to get the rear lens cap to hold as tightly as the front.

The stowed configuration of the lens caps came about by accident. Joe didn’t like how the lens caps just hung out in the breeze when open. Ironically, he noticed that the micro optic was short enough such that the front lens cap could reach the rear lens cap, and they could nest inside each other. He added the same ridge from the rear lip to the outside of the front lens cap, and they snapped together perfectly. The lens caps stow on the left side of the optic.

The body of the IO Cover has cutouts which expose the battery housing/brightness adjustment knob, and the elevation/windage adjustment caps. The brightness adjustment knob's numbers are covered, except for the top one, which indicates the level of brightness that the optic is set at.


IO Cover Rev 5

Caps closed

Caps open and stowed


Installation and Operation - Installation is simple. The IO Cover is slipped over the front lens and worked/stretched over the optic, with the rear ring going around the rear lens last. It's removed by reversing the sequence. Joe states that "The IO Cover is designed to work with one hand (left or right) using gross movements, even when wearing gloves. There’s nothing small to fiddle with. Just press the lens caps on. Swipe them open using the big tabs and snap them together. Twist them apart.

The concept is to act as a functional cover for when the weapon is in use. The current bikini covers are a no-go as they are a slow two-handed operation with no retention. Just like the Micro is in an “always ready” state, the caps should be open and linked together out of the way in most ideal environments.

When the conditions turn nasty and most guys go home, the caps can be twisted apart and the lenses covered with one hand. If the opportunity presents itself, the caps can quickly be swiped open with one hand and the threat serviced. Even though they may flap around a little in the open position, they never move enough to impede the sight picture under recoil or movement or weapon orientation. Once there is a lull in the fight, they can be smashed together with one hand into the stowed position instead of hanging out in the breeze for the duration of the fight. Even so, I've beefed up the hinges and the underside as well as some other little detail changes. I’ll be posting pictures of the latest prototypes when I get them this week.

While this is intended as more of a patrol cover for inclement conditions, it could also do a decent job of keeping the lenses clear in a vehicle rack as some have noticed."


Rear view

Top view

Low profile LaRue mount

Tall ADM mount



Observations/Notes -The Rev 5 prototype shown here is molded in a foliage green/grey colour. IO Covers can be molded in just about any colour, once production starts and the order for any particular custom colour is large enough. It's also a great option to painting the Micro, and the additional protection that it provides for the optic is a plus.

Once installed, the IO Cover is very secure; it fits like a glove on the Micro. The lens caps are quick to deploy when needed; a swipe of the hand is all that's needed. You essentially put your hand over the optic, and spread your fingers apart, with the thumb catching one tab, and some other finger catching the other, popping the caps open. Shooting can commence immediately, if there's no time to stow the caps. The issue of the caps being in the way when not folded is overrated. Your eyes 'look past' the lens caps sticking out to the sides, and while they're in the field of vision, they don't really block you from seeing anything, as your binocular vision takes care of it.

Stowing the caps is also accomplished easily with one hand; fold the rear with the front one on top of it, and press. The front one nests inside the rear one securely. Pull the tab on the front one to 'un-nest' them, fold them around to the front and rear, and press to close.

The configuration of the caps is one of the most common points of discussion. Many people (like me), with the full size Aimpoint Comps, have the lens caps open downwards, so that they're contacting the top of the rail. While this may work for most configurations, there are times when it won't work, as in very low profile mounts. There's not enough distance for the caps to stay out of the way. Another instance is when magnifiers are used behind the optic. Folding over the top may be an option, but it really boils down to the individual application and personal preference. With separate lens caps, either one can be rotated to accommodate that, but with molded/integral ones, you don't have that option, so the one that worked with the least interference was chosen - folding to the left. There are many possible combinations, all with their pros and cons. Complexity also adds cost, so there's a good reason to adhere to the KISS principle. When folded and stowed, the caps are quite low profile. Viewed from the back, they form a 'I' and the optic forms an 'O', hence the name 'IO Cover'.

When I first saw the pictures of the prototype IO Cover, I immediately recognized it was something that I wanted, and had use for. I'm obviously not alone, as the project has been very well received by end users and is gaining momentum. Let's help get it going! Follow the Kickstart link to support it. This project will only be funded if at least $20,000 is pledged by Monday Oct 22, so time is of essence.

Update - the project is a 'go', and TangoDown will be marketing the IO Cover.

TangoDown Front Sight Flashlight Adapter

1/1/13 - The FFA-01 Front Sight Flashlight Adapter from TangoDown is a fixed front sight that mounts in front of a SureFire X-300 light, allowing access to the rear switch and providing the longest sight radius possible.

Background - Figuring out where to mount a weapon light is something that an individual needs to figure out for themselves. Given a quad rail on a rifle, you have quite a few different mounting options, depending on the mount and configuration of the light. One option that has gained popularity over the past couple of years for CQB is to put a light on the top rail at 12 o'clock, on rifles that don't have a fixed front sight gas block on the barrel. The advantage to doing this is that it's an ambidextrous setup, and that the light is not blocked when going around corners by doorways etc. Typically, the SureFire X-series lights have been the light of choice, as their short length and low profile make them suitable for top rail mounting. However, when mounted on the top rail, the question then is: where to mount the front backup iron sight? A folding front sight won't fit in front of the X300 light as it'll obscure it, and has to be placed far back enough to allow easy access to the toggle switch, reducing the sight radius.

A note from the inventor of the FFA: "The most often overlooked reason for having a fixed-front sight post on a combat rifle is that todays weapon lights are so bright they often overpower red dot optics. This is the primary reason the FFA was invented. Most professional gunfighters can tell a story of how, after inserting a few terrain features away from an objective, at night, they forgot to dial up the intensity of their red dot before they made entry. Then, while utilizing white light on interior rooms, they could not see their aiming point on a target because their light overpowered their dot. Without a fixed front sight post on your weapon that is readily available, you are forced to let the rounds fly and hope for the best, because that is all you can do at that point. There is no time to flip anything up or find another aiming point. This very scenario happened to me, and that is why the FFA was born. As for the 12 o'clock light position, just have any non-believers shoot through every port on a VTAC barricade, at night, while identifying their target with a white light. That usually drives the point home."

Description - The TangoDown FFA-01 is a fixed front sight that mounts in front of an X300 or X200 (note that it will not fit the new X300 Ultra), providing the longest sight radius possible and allowing unrestricted access to the rear switch. It does this by its donut shape, encirling the head of the light instead of blocking it. The FFA-01 has a clamp-style mount, requiring it to be slid onto the rail from the front. A screw secures it in place (using a 9/61" allen wrench, not supplied), acting as a recoil lug in a rail slot. It's a very solid mounting scheme, and it also serves to protect the lens of the light from impact damage.

The body of the FFA-01 is made of 4130 steel and has a black manganese phophated finish over a blasted surface. It has lightening cutouts/holes and two ears that protect the front sight post. The post is unusual because it has a smaller tip at the top, rather than being of the standard width. This was done to allow more accurate sighting on targets at longer distances. The post is adjustable for elevation by loosening the 5/64" allen set screw in front and rotating the post by hand. It's heat treated, and would take quite a big smack to hurt it.

Note that the FFA-01 is for not designed for use with rifles that have the standard M4-style fixed front sight gas blocks.


TD FFA-01 sight

With X300

Inforce WML


Observations/Notes - The FFA-01 is very sturdily built, and I have little doubt that it'll stand up to impacts as intended. While it's designed to fit the SureFire X300 light, I also found that the Inforce WML also works with it. I prefer the WML to the X300 as I find the design and location of the switch better than that on the X300. When mounted in conjunction with the FFA-01, the lights are positioned a few slots further back than if they were mounted at the end of the rail. This means that the hand will also be further back on the rail to actuate the light. It's a compromise, but preferable to the alternative on shorter handguards. I did not see any effect on the spill beam of the X300 or WML, when I tried it out.

Note that the front sight and light have to be removed from the rail in order to change out the batteries of the SF X200/300 lights, since the lights need to be slid forward and off the rail in order for the battery compartment to open. Return to zero can be verified by checking the co-witness with the red dot before and after. This is why the Inforce WML might be the better choice as it can be rocked on and off the rail with a bit of wiggling while the FFA-01 is there, if battery field replacement is a concern.

The sight picture is very reminiscent of the Magpul MBUS sights, which have a similar 'ear' configuration. The FFA-01 ears are about .585" across the inside of the ears and .840" across on the outside. It's a wider/different sight picture from standard but actually fills up the large rear aperture more, which makes it quick to align. The FFA-01 is about as close to having an integrated front sight on top of your weapon light as you can get.


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



View from front

View through rear


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.


Mounted behind MRDS

Mounted behind T-1

Angled up

Aimpoint Comp


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.


Side view through MRDS

MRDS and T-1 sights pictures

Flip Mino camera


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 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.

Diamondhead-USA Sights

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.


Front sight

Rear sight

Large vs. small aperture

Large aperture

Small aperture

Through T-1

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.

SIghts in the lowered position


Front sight 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.

Auto-Ranger front sight

Different post heights


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.


American Defense Mfg. Mounts

11/11/12 - American Defense Manufacturing, LLC, more commonly referred to as 'ADM', has been around for a few years now, and I figured it was about time I featured some of their products on the site since I've been using them for a while.

American Defense Mfg and the QD Auto Lock System - ADM is a Wisconsin-based company, and manufactures all of their products here in the USA. ADM developed the patented QD Auto Lock Lever system which is a means of attaching a base to a Picatinny rail. The system can be applied to optics and accessories alike. Some of the features of the QD Auto Lock Lever system are:

  • Does not require tools for adjustment
  • Can be adjusted with a finger or flat blade screwdriver
  • Lever can be configured to lock to the front or the rear
  • Large clamping surface to ensure maximum rail engagement
  • Fully adjustable to fit both in spec and out of spec rails

All ADM mounts and rings are manufactured out of 6061 T6 aluminum with a Type 3 hard coat anodize.

There are quite a few different variations of QD systems for rail systems, such as those by LaRue and A.R.M.S. The ADM QD Auto Lock system utilizes a lever which has a lock button that keeps it in the closed position until depressed. The lever has an increasing radius, rounded cam profile that is shaped such that locking the lever tightens it and unlocking it loosens it. The cam profile bears against a spring loaded rail clamp; moving it in and out from the rail. The lever pivots on the end of a cross bolt, which also serves as a recoil lug. The threaded end of the bolt has an octagonal adjustment nut on the end, which seats in an octogonal recess in the side of the base. When seated, the nut is prevented from rotating.

When the locking button is depressed, the lever is allowed to open. Swinging it open 180° from the locked position loosens it up such that it can be pushed towards the opposite side, compressing the springs under the clamp, unseating the adjustment nut from its recess. The adjustment nut can then be rotated to loosen or tighten it. There are 8 positions for every full rotation. The nut is rotated to achieve the proper tension for the lever, such that the clamp is tight on the rail. It's a system that works well, and has been adopted by industry partners and affiliates such as Daniel Defense, TangoDown, Noveske and Vltor. In fact, Eric Kincel from Vltor had a hand in the design of the QD Auto Lock System.

Starting out with a couple of mounts for the popular Aimpoint M2/M3, ADM has expanded its product line to include mounts for the Aimpoint M4, Micro, Eotech, mini red dots, scope rings, Trijicon scopes, lights, lasers, bipods, and night vision. Where applicable, mounts are supplied with wrenches and threadlocker (Vibratite).

High Profile Aimpoint Mount AD-68 H - The AD-68 is designed for the M-68 CCO (Aimpoint), and is available in standard, low, high and cantilever configurations. The standard height AD-68 features an absolute co-witness with the standard iron sights on an AR15, and places the center of the optic tube at 1.52" above the top of the rail. The low mount places the center of the tub at 1.10", and the high mount shown here places it at 1.69", for a 'lower third co-witness'. The irons appear in the lower third of the Aimpoint tube - this is the preferred height for most shooters I know. The mount is marked on the bottom 'AD-68-H'. It weighs 3.5 oz, and comes with a hex wrench and Vibratite thread locker.

The 30mm ring is split vertically and is secured with four hex head screws. The bottom ones are tightened to the base first, then the top two. You may notice that the rings have two screws at the top, whereas the earlier version had three.


AD-68 H



Aimpoint T-1 Micro Mount 1 Piece SOCOM Height AD-T1-11 - The AD-T1-11 is a one-piece unit that's compatible with the Aimpoint Micro T-1 and H-1 micro red dot sights. 'SOCOM Height' is lower third co-witness. It's also available in low and absolute co-witness heights (AD-T1-L and AD-T1-10 respectively). The AD-T1-11 weighs 2.75 oz, and comes with a torx tip wrench and Vibratite thread locker.

The body of the mount is basically a box, open at the bottom, with a single locking lever. It's supplied with four torx tip screws which replace the small hex head screws that the Aimpoint Micro comes with. Pictured here is the H-1 Micro. I've illustrated the lever below in the locked and unlocked positions, as well as the adjustment nut in its seated and unseated positions.



Lever locked and unlocked

Adjustment nut seated and rotated


SCAR Mk20 mount AD-Delta-30 - This Delta-series scope mount was developed in conjunction with FNH to exceed SOCOM requirements for the Mk20 SCAR heavy sniper rifle system. I'm a bit confused, as this specific mount is marked AD-RECON-FN on the base (and AD-DELTA-30 on the box), and ADM has a Recon series of scope mounts as well. The most noticeable difference between this mount and the Recon mounts pictured on the ADM website is that the rings are split horizontally, as opposed to vertically. They're also solid, as opposed to skeletonized like the other ADM rings. The mount is available in 1" and 30mm tube versions from MWI, with a choice of black or FDE (shown here). The height from the top of the rail to the center line of the ring is 1.505".

It's a heavy mount (8.5 oz), and solid as hell. The base is thick, as well as the rings. It has two QD Auto Lock levers. If you want the mount issued with the Mk20, this is it. As far as compatibility with scopes, the distance between the outside of the rings is 5.36" and the distance between the inside of the rings is 3.4". It's illustrated below on the SCAR-L with a Nightforce 2.5-10 x 32 optic. The mount has zero cant.

Marked AD-Recon-FN

Nightforce scope installed



Notes/Observations - Another thing that sets ADM mounts apart from the others is the distinctive angular, octogonally-shaped rings. Some like it, some prefer a more rounded shape. Either way works for me, and it doesn't have any effect on perfomance, only aesthetics. The angular mounts do compliment the lines of the Vltor MUR and VIS upper receivers, in my opinion.

Adjustment of the QD Auto Lock system is very easily accomplished, and I usually adjust the nut so that it takes a firm push to lock the lever. After a couple of hundred rounds, it's a good idea to check the tension on a new mount again. ADM mounts have proven to be well made, solid and repeatable.




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