What is this unheard of rifle? It was a far-from-popular assault rifle that was sold for a couple of years (in pistol grip form) in the early to mid-1980s in the United States. The AR-100 is the civilian version (semi-automatic) of the South Korean Daewoo K2 rifle. The K2 was designed after the Vietnam War. The South Koreans observed the main assault rifles being used in the conflict; the AK-47 and M16. They decided the 5.56x45mm used by the M16 was a good round as it was accurate and lightweight, but the AK had the best reliability and was easy to maintain. A few chalkboards later and you've got a rifle with barrels being made by Colt, an AR-15-like lower-receiver (no parts interchangeable), a piston return system like an AK-47, and a gas valve adjuster like an FN FAL. In short, you have a super-reliable rifle using the accurate 5.56x45mm round in Colt barrels; the accuracy of the M16 with the durability of an AK-47. Due to their construction, these rifles accept some M16 accessories as you'll see in the following photograph.
In the photo, you can see that, even though no internals are interchangeable, the rifle will still accept bayonets, slings, and magazines made for the AR-15/M16x# platforms. Our particular rifle is equipped with an M7 bayonet, surplus M16 sling, and the original, brass-coloured Colt magazine that the rifle is/was issued with. Also, you may have noticed a bit of a cylinder shaped area sticking out to the right-hand side of where the stock meets the receiver. As previously mentioned, this rifle uses a piston return. This means all the cycling parts are in the receiver and return tube above the barrel unlike the M16 (which has the recoil spring in the stock). What should they do with this stock then? They decided to make it into one of the best side-folding stocks available.
This rifle is also, as mentioned, very accurate. Part of the reason would be its superb peep-hole/aperture sights very similar to those used on the AR-15 series of rifle. All one has to do is look through the rear sight and, since the front sight is encircled, "align" the circles to where the front sight post is in the middle of the sight picture.
Another similarity between this rifle and the AR-15/M16 would be the fire mode selector switch. Unlike the AR-15 which moves from "safe" to "semi" in a 90* rotation, this rifle switches from "safe" to "semi" in a 180* rotation. Some people may dislike this, but I've never had a problem with it. The safety switch is in the half-way position in the photograph. Aftermarket safeties do exist that transform this into a 90* rotation safety, and I do recommend this drop-in modification for any Daewoo.
Unlike the the AR-15, this rifle features a gas valve adjuster as to improve the reliability even more. This is so if your rifle is getting dirty and not cycling well, you can adjust how much gas is being put into the upper tube to force the cycling piston back. We've never had to adjust ours, but it is nice knowing you can in the event you have to.
In my honest opinion, this is probably the best semi-automatic rifle I've handled. The accuracy is excellent, it's very reliable (manufactured before 1987 with zero malfunctions to this day), and the take-down is also pretty easy. If you're looking to get a new assault rifle and have about $1,300.00 you want to spend (the only real downside of the rifle; price), the Daewoo K2/AR-100 is, in my opinion, the best way to go. Though they won't match an AR-15 in how must customization can be done, quad-rails and many other useful accessories do exist for the Daewoo. I must mention, however, that the purple-tinted rail you see in the photographs above is an aftermarket product from the 1980s. If you're wanting a rifle that will perform very well in even stock formation, though, the Daewoo is a great way to go.