Height over bore, or to put in layman’s terms; The distance between the point of aim to the bore of the weapon itself.
Traditionally it has always been considered better to have as little height over bore as possible, but as technology and tactics have progressed, the application of height over bore has become a hugely central topic of weapon set up debates.
It used to be that height over bore (HoB) dictated the fundamental design of a weapon, from the very outline, you could see that the designer was attempting to get the sights as close to the bore as possible, even compromising on other areas of the design to make this achievable.
Looking at earlier rifle designs from the last century, the placement of the stock is designed to allow the shooter to shoulder the weapon, aim down the sights, being shaped to allow the shooter to aim at a set of sights placed directly atop the barrel, with a very low height above bore.
Eugene Stoner’s AR10/15/18 pattern rifles changed all that, designed to be controllable in both fully automatic and rapid semi-automatic fire, everything from the stock and bolt carrier group was designed to be in as straight a line as possible from the barrel.
Meaning that the recoil forces from the bolt carrier group are transmitted back into the users shoulder, causing very little muzzle climb in the weapon. Ergonomics sometimes have to work around the design of a machine, this being very much a case in point with the M16/M4 family.
The higher set sights on Stoner’s AR15 pattern rifles form that distinctive carry handle and front sight post outline, that continues to remain rather unique in firearm design. This was necessary to ensure that the shooter could shoulder a rifle comfortably, working around the “in-line” design of the weapon but still have a workable set of sights.
The biggest trade off with such a large height over bore is that within 25 yards or so, there’s a noticeable discrepancy between point of aim and point of impact, often causing issues with the muzzle being behind an object that the sight itself clears by a wide margin.
Many years went by with the standard 2.6” HoB for the AR15 pattern irons, and once optics such as the Aimpoint 2000 and Trijicon ACOG started to be mounted directly to carry handles, the HoB shifted even further up. The introduction of the flat top receiver (and gooseneck rails for older AR uppers) caused the shift to come further down, but more recently, there has been a shift back towards the taller mounting options.
So where does the Unity Tactical FAST Micro Mount come in?
Recently, we’ve become increasingly more concerned with a rifle’s ability to shoot well at night than any other factor. One of the biggest barriers to shooting well at night is the ability to aim passively through a red dot sight with NODs, whilst continuing to hold your rifle in a comfortable and effective manner. Hunching your head down and canting it to one side (as many NOD setups dictate) is just not comfortable, and this is one of the many reasons why high HoB sights are making a comeback.
Comfort is central to accuracy, hence why the tactical shooting community started to look at riser options for their night fighting rifles. Moving up from the 2.6” height on a set of M16 irons to 2.8” (lower 1/3 co-witness) helps a little, moving even further to 3.33” (1.93” height above rail) helps even more… Unity Tactical however, have taken it a stage further with their 2.26” mounts, measuring a staggering 3.66” total height over bore. So the inevitable question is, does it work?
Before we get into the review, I’d like to clarify my relationship with both the manufacturer and the supplier. Aside from being incredibly interested in Unity’s ongoing product line, I have absolutely no relationship with UT.
As for my relationship with Tactical Kit (who sourced and supplied this mount), I’ll occasionally be sent items for the purposes of review, but this is not one of those times. The FAST mount was paid for out of my own pocket, and as such, there was no expectation of a review in general and certainly no obligation to sing its praises unjustly.
Onto the mount itself:
I’ll start by looking at the construction and quality of the mount before I consider the fundamentals of an ultra high mount. The material that is prodominantly used is 7075-T6 Aluminium, this is then type III hardcoat anodised in either Black or FDE.
7075-T6 Aluminium provides a strong yet light material to form the mount, with most of the material cut away, lightening the mount further still. The hardcoat anodising ensures that the aluminium doesn’t suffer from any oxidisation, improves the durability of threaded components (preventing “galling”) and also gives the component itself that desired colour.
The mount is held onto a rifle via the incorporated 20mm Picatinny rail mount, this comes as standard in a cross bolt type fixing (using T25 Torx bolts). There is a QD option available (OEMed by American Defence Manufacturing) if you need to remove your optic on a regular basis, but it’s not something I feel is needed on a primary optic.
I can understand that in very specific cases it might be beneficial for some people to have this QD element on their FAST mount but as a rule, I prefer to keep my optic attached to my rifle at all times.
Recoil lugs are present on both the “rail to mount” and “mount to sight” interfaces, the rail recoil lug is offset to the front, allowing for the installation of the optional QD type lever bar. The upper recoil lug fits within the Aimpoint T1 type sight footprint, which itself has become a standard for the majority of micro red dot sights.
Contained within the mount is a complete set of back up iron sights (BUIS), eliminating the need for a standalone set of emergency “last ditch” sights. Admittedly, if you choose to use both the front and back BUIS within the same mount, the sight radius narrows down to less than an inch.
This will make zeroing the rifle somewhat… interesting. But, it’s certainly usable and far more accurate than shooting through an optic with a dead battery. I’d have liked to see a smaller pin being used, or even a chevron type point, but it’s a sight of last resort, so I’m not too worried.
Pairing up the rear peephole type sight with another integrated front post sight (such as the LEAF type sight for my D-BAL) allows for a full carbine length sight radius, whilst not taking away any vital rail space. This might not seem like a game changer to most people, but it’s essential if using a magnifier.
Windage adjustment of the rear iron sight is accomplished via the side, i small screwdriver, Aimpoint tool or the cap of certain red dots (such as Holosun) will fit perfectly.
The elevation of this sight is adjusted simply by screwing it further in or out, a 5/64” Allen key is recommended, but you MIGHT get away with using a decently made 2mm Allen key. Both front and rear sight are removable if you should want to retain your own separate BUIS, and both come with a tension grub screw to help keep that emergency zero set and locked once adjusted.
It’s worth pointing out that you’ll need a good set of imperial Allen “hex” keys and Torx star drivers if you delve into the world of “real steel” accessories. Using metric or poor quality ones will cause damage to the mount, become damaged themselves or just refuse to work at all. Buy decent tools once and look after them, they’ll last you a lifetime. Some accessories such as BCM’s Gunfighter Mod 3 grip (reviewed here) will come with the right key to install the item, but Unity Tactical leave the tool provision up to you.
As mentioned, the top of the mount is machined for an Aimpoint Micro Red Dot footprint. This means that most sights such as their T1/ T2 series will fit perfectly and other sights such as Holosun, SIG, Primary Arms and Vortex should also fit as long as they’re built to Aimpoint’s dimensions. Cheap airsoft clones might fit, but there’s no guarantee.
Almost every edge of the mount has been machined with a subtle chamfer, this makes the mount surprisingly snag free. Whilst you’d expect a mount like this to be rather unforgiving to slings or cordage etc, it’s far softer on the edges than the flat top rail you’ll be mounting it onto.
The FDE colour is a nice looking “coffee bean brown”, and although there’s no guarantee that others will be the same (there’s actually an explicit disclaimer saying they won’t), there is a definite difference between my FAST Micro and my FTC mount (presumably from another batch), but they’re both close enough to look right. Every one I’ve seen so far has a distinctly bronzed finish, so don’t expect it to match up with some of the darker or more tan FDE accessories out there.
The only test that matters though, is how it performs. Is it worth the high price tag or are you better off just buying a cheap riser block? It’s a valid question, I personally feel that the FAST mount owes it to the customer to justify its high price by at least offering you one thing that nothing else on the market can do, or do what others can, only much much better. So does it? Well, I’ll tell you what I’ve experienced and let you make your own mind up.
I’ve found that the unity height is almost perfect for a “head up” posture, making it far easier to keep both eyes where they need to be. It allows the user to keep a solid cheek weld on even the most low profile of stocks, whilst keeping that essential situational awareness and peripheral vision that’s easily lost if dipping your face deep into the stock.
You might find that when you first use the FAST mount that you have to “untrain” yourself from your normal shooting posture into a more natural stance when holding the rifle, certainly if you’re used to a lower 1/3 red dot height, it feels rather unusual. But it doesn’t take long to get used to the higher profile of the Unity Tactical FAST mount and once you’ve got used to it, you might find it incredibly beneficial.
Unity Tactical actually provide a mock FAST mount for those who are sitting on the fence, simply follow their instructions and print out the mock sight (found here), a little Blue Peter magic later and voila! You can work out if the FAST mount is something that could work for you.
Using the FAST mount with head mounted night vision devices (HMNVD) potentially shows the single biggest reason for choosing this mount. Usually when passive aiming, you often end up having to bring your head down to the weapon, but with the FAST mount, your easily able to bring your weapon to your eye. It’s very natural in practice and you’ll soon find that instead of having to search for the dot, it magically appears exactly where you’d expect it when you bring up your weapon.
An additional benefit with the height of the FAST mount is that you also won’t constantly knock your HMNVDs against the upper receiver, something I’ve found is inevitable when passive shooting through lower 1/3 height red dots. It’s something that ranges from plain old annoying and inconvenient, right through to dangerous and costly. The FAST mount does a good job at negating the risk to both yourself and your expensive night vision devices, and whilst it might not be the sole reason to buy one, it’s a valid consideration.
There’s also a significant benefit to those who are not using HMNVDs, one that is incredibly well demonstrated by The Reptile House’s earlier review of the same mount. The head up posture is not only better for tactical situational awareness, it’s also incredibly comfortable. He demonstrates it far better than I could and I’d recommend heading over there for an alternative view on the FAST mount.
So, negatives… The cost is always going to be a barrier to many peoples budget, at around £185 for the mount, it’s more expensive than many of its competitors, but nothing else currently on the market offers everything that the FAST mount offers in such a well rounded, light and refined package.
There’s also the obvious question of the PTS licenced version (along with the inevitable Chinese clones), but from personal experience, PTS don’t continue to offer the quality that they used to with their Magpul licenced products, their Unity Fusion Hub had a number of fundamental flaws, and theres no guarantee that PTS will provide a mount thats usable or even a mount that’s significantly cheaper than the original Unity Tactical design.
I am scratching my head as to why Unity Tactical would ever licence their products to an airsoft manufacturer, from my understanding, it offers much more risk than reward. Ultimately those risks caused PTS to lose their Magpul licence and will undoubtedly cause Unity Tactical more than a few headaches.
There’s also a slight bend or offset on my internal post sight, it’s not a major concern as I’ll not be using it (I prefer the longer sight radius offered by my LEAF sight) and it’s also easily remedied by adjusting the sights to match, but it is there. I’d also have preferred to have seen a smaller pin or even a steep chevron point make up the profile of the sight, it would have allowed for a much more accurate method of adjustment. It’s really not a dealbreaker though, it’s something that is surplus to most peoples requirements and it’s also a fixable issue that may not even exist on your unit.
The big question remains, would I recommend this mount to a friend? Well its not a simple answer, the unique ability of the FAST mount is something that’s going to have an obvious appeal for specific builds (such as my “night fighter” GBBR), it offers a wide range of benefits and is arguably the best solution for the requirements I have within that platform. However, you will pay a hefty price for the benefits it gives you.
Overall though, if you’re willing to spend triple figures for a high quality optic, theres no reason to not spend the same on a high quality and uniquely functional mounting system to go with it. There’s also the consideration of Unity Tactical’s Flip To Centre magnifier mount (reviewed here), which I’ll be covering in another, upcoming review.
I had to clutch at straws to find a negative on this review, if you’ve got the money and either have a requirement for a tall mounted optic or run HMNVDs, this is the mount to use. Overwhelmingly, this mount is going to offer what it says on the box. It isn’t within everyone’s budget, but for those with NODs, its a drop in the ocean.
The FAST mount, along with the majority of other Unity Tactical products is available in the U.K. from Tactical Kit.