Shooters can be very pickly when it comes to iron sights. I know there are guys who can shoot just as well with AK-47 irons or Winchester buck-eyes as they can with U.S. military aperture sights, but most of us have our preferences. For you folks running ARs, FAB-Defense manufactures an excellent set of affordable polymer back-up iron sights known as FBS and RBS. Here’s the G2 . . .
A set of BUISs is essential for any rifle that’s going to spend time out in the bush. If your rifle is just a range toy or a 3-Gun competition gun, then you probably have other options if your scope breaks, but a bush gun is different. You might be 20 miles away from camp when your scope fogs up, the batteries die, or it falls off and breaks. Fold-down BUISs are mandatory on those rifles featuring top picatinny rails.
The most important feature I like about the FAB-Defense sights is that they provide a very intuitive sight picture. If you’re familiar with the sights on an M-1 Garand, M1A, M-1 Carbine or Model of 1917, you’ll be right at home with FAB’s sights. I learned on both the U.S. military sights found on M-16A1, as well as on the HK type globe sights, so these two types of military sights have always been my favorites. So the closer a set of BUISs can mimic the traditional G.I. or HK sight picture, the better I like it. The FAB-Defense sights fit that bill.
Unlike a traditional G.I. sight picture, however, the “ears” on the FBS turn inward instead of outward. So in that sense they are more similar to a traditional HK-93 sight picture. But that’s a pretty easy transition to make for someone who shoots well with G.I. sights.
The FAB Defense sights are teh same height as a standard Ar-15 sight, so they offer an absolute co-witness with an optic such as the Aimpoint T-2 and LaRue mount.
I also appreciate the compact design of these sights. They’ve been designed to have a low, streamlined appearance. The sides are beveled so that there are no sharp edges or corners to snag on stuff. They kind of remind me of the lines on the F-117 Stealth bomber. The shape also allows you to flip the sight up into position using only your thumb.
The FAB-Defense sights are made of a type of technopolymer, which results in an incredibly lightweight set of sights. The RBS weighs 1.5 ounces, and the FBS weighs only .88 ounces. Nonetheless, the manufacturer claims that the sights “exceed Mil-Spec strength requirements,” but obviously, that’s a claim that’s hard to evaluate. Having said that, you don’t need to spend much time with these sights to gain confidence in them.
The RBS features an L-type flip sight with dual apertures, reminiscent of the M-16 series of weapons. To recap for those of you that are rusty on how the M-16 sights work, here is a quick primer: The unmarked (small) aperture is used for most firing situations. Conversely, the “0-2” (large) aperture on an M-16A2 and M-4A1 is used for short range work – in theory that’s 0-200 meters, but most soldiers will switch to the small aperture for anything over 50- 100 meters. I always qualified using the smaller aperture, and I typically shot 39 or 40 out of 40 on pop-up quals.
The 0-2 aperture is used only when the rear sight is turned all the way down. When in the down position, the “8/3” (300-meter) mark on the elevation knob is aligned with the index mark on the left side of the receiver. The elevation knob is used to make shots from 300-800 meters; it works simply by raising the rear sight. Using the small aperture in conjunction with the elevation knob, the shooter can, in theory, hit targets from about 300 to 800-meter downrange. Obviously, YMMV.
To be fair, it’s worth noting that the FAB-Defense RBS does not have the same type of elevation adjustment found on the M-16 sight. The RBS’s similarity is limited to the fact that it features dual apertures in a leaf sight arrangement. On the RBS, the leaf’s default position is a CQB aperture similar to the “0-2” aperture. The RBS can only be flipped down when the L-shaped flip sight is set in the 0-2 position.
The front sight post is made of steel, and is .07 inches wide. That’s the same as the front sight post on the M-16.
One thing I really appreciated about the FBS is that the front sight post can be raised or lowered by simply turning a dial that’s protected so it can’t be accidentally knocked out of position. It is held in position by a detent that snaps positively into position with audible and tactile clicks.
It’s a fast system. I could quickly obtain a “rough” sight-in by simply picking out a rock at 50 yards and shooting a round and then using the thumb of my non-shooting hand to rotate the dial until hits are achieved. This could be done without taking my firing hand off the trigger finger. The process is so fast it’s possible to sight in the elevation in less than 30 seconds using this technique.
I’m not aware of any other system that’s as fast as the RBS. As readers may be aware, adjusting the front sight on an AR-15/M-16 requires the use of a tool (typically a 5.56 x 45 cartridge).
I had previously bought a set of the Magpul BUISs, but the RBS and FBS are superior. First, the FAB-Defense sights are lighter. They’re also smaller, as shown in the comparison photos below:
And unlike the Magpul BUISs, the FBS doesn’t require a tool to adjust elevation. I’m not really sure what Magpul was thinking when they thought that a proprietary tool was a good idea, and it goes down as a rare misstep for that venerable company. However, FAB-Defense clearly gets the win.
Like the Magpul sights, the FAB-Defense sights are available in OD green and tan.
I’ve been running the RBS/FBS for about a year now can recommend them without hesitation, especially for folks on a budget and are looking to save money on their AR build.
Specifications (for both RBS and FBS unless specified below).
Length (Folded): 52 mm (2 inches)
Length (Operational): 30mm (1.18 inches)
Height (Folded): 14mm (.55 inches)
Height (Operational): 42mm (1.65 inches)
Width: 32 mm (1.26 inches)
Weight: RBS = 30 grams (1.06 ounces); FRS = 25 grams (.88 ounces)
Colors: Black, OD green, tan
MSRP: RBS = $52 / FBS = $34
Ratings (out of five stars):
Overall Rating: * * * * *
Better than any polymer sights in their price range. Bar none.