It has been fashionable for many years—decades in fact—to bash Colt. I’ve indulged in it myself and, to be truthful, they deserved a lot of it. But one thing they didn’t deserve was the accusation that the company was unaware of progress. Colt was, for better or worse, lashed to the Procrustean bed of mil-spec. They could have found a way to make a perfect barrel, one that never wore out or lost accuracy, but if it wasn’t mil-spec, the government wasn’t interested.

For a long time now, shooters have been unhappy with the 5.56. (For the record, I am not one of them.) They pined for the good old days, when men were men, and men shot .30-caliber rifles. The first ArmaLite, the AR-10, was chambered in .308, and an awful, under-engineered mess it was. We have spent many years of late refining, perfecting and properly engineering the .308 Stoner system, and it has gotten to the point where manufacturers have been achieving success.

A Bigger Bore
Now Colt has shown up with a .308 rifle, the LE901-16S (and to save all that typing, I’m just going to call it “the Colt” from now on). What is more, they’ve designed it so you can swap out the entire .308 upper assembly for a 5.56 upper, should you wish. Wow. When I first asked for one, I was told they were still in the prototype stage, and it would be some time. When it was delivered, the Colt arrived in several stages, the 5.56 upper and conversion first, then the complete .308 rifle a few weeks later.

Giddy with excitement (OK, I’m easily amused), I tossed the parts in the car and headed to the range, where I discovered that the two uppers worked just fine. For the initial range trip I just took the rifle and upper, and a batch of Hornady ammo. While you can complain about a lot of things, one thing you can’t complain about is Colt’s factory sight-in method. I used the factory settings and only had to give them each a single click to get them dead-on for me.

But I’m getting ahead of myself. What about the rifle?

The new Colt is a .308 Stoner-system rifle, using the direct-gas impingement system. The magazines it uses are Magpul (the rifle comes with a pair of them)—a modern, polymer recreation of the original Stoner magazine (also known as the SR-25 pattern). You will not find yourself with a rifle hosting an orphaned magazine pattern here.

Compatibility in Key Areas
OK, while making it a .308, Colt worked hard to keep it as compatible as possible with existing 5.56 parts and accessories. The handguard is an integral part of the upper, all of it machined from a single forging, so you need not worry about what rail system you are going to install, because you aren’t. Also, the front sight assembly is a folding design, so you need not concern yourself about an upgrade there either. The receiver extension is a mil-spec-diameter 5.56 tube, so if the provided stock just doesn’t do it for you (and I don’t know why it wouldn’t; it’s a Vltor IMod), you can simply take off the existing one and swap it for the one of your choice. Ditto the pistol grip, but you can swap it for the one that feels good to you, if you wish.

However, the real action is in between those details. Let’s talk about the receiver. First, to fit a magazine that can hold a .308 cartridge, Colt had to make the magazine well larger. They did so without making the rear half of the receiver larger, so not only are the other 5.56 accessories things that would fit, but the trigger components will, too. You can fit your favorite match hammer/trigger combo, if you feel the need, as the pins are the mil-spec diameter, not the old (larger) Colt diameter. If you are cool with a mil-spec trigger, great. If not, you have the whole panoply of aftermarket triggers to choose from.

Ahead of the trigger and selector, you’ll see some extra controls. The Colt LE901-16S is an ambidextrous rifle. There are magazine release and bolt release controls on both sides. Colt used the extra aluminum they needed for the .308 magazine well as location points to build in the extra controls. They aren’t bolt-on extras or afterthoughts; they’re integrated into the receiver. You can use the rifle as you’ve been accustomed to all these years, or learn the extra controls. Also, Colt figured out how to make a single magazine catch contour work with both 5.56 and .308 mags.

On the end of the barrel Colt has installed a Vortex flash hider, which in the opinions of many is the best flash-hiding gizmo short of a suppressor. You might find a .308 load that produces a lot of flash out of a rifle with a naked muzzle, but in this Colt it will be tamed.

In operation, the Colt works like every other AR you’ve ever handled, except some things are bigger. Magazines in and out, selector selection, trigger pull, case ejection—all the same.

Opening the action of the .308 is just like it is with a 5.56: Push the rear pivot pin to the side, hinge the action open, and pull the bolt, carrier and charging handle out of the rear (with the usual jiggling of parts, of course).

However, take a look at the magazine well. Notice that not only is it bigger, but the front pivot pin is offset. Hmm. When you open the action to clean or disassemble, the 5.56 upper won’t pivot down all the way, as the forearm bottoms out against the front of the lower. No big deal. But this is where it gets interesting. The 5.56 upper has its front pivot pin in the customary location on its receiver. To install the 5.56 on the .308 lower, push both .308 pins to the side of the lower receiver and lift off the .308 upper. Remove the .308 buffer weight (it’s marked “308”) along with its recoil spring, which is markedly different from the 5.56 spring, so you can keep them straight. Install the 5.56 spring and weight.

Now take the 5.56 upper (Colt’s or yours, any will fit) and take that odd-shaped “U” of metal that came with the Colt 5.56. Notice the pivot pin in the adapter? Push it to the side and use it to secure the adapter to your 5.56 upper. Then slide the adapter down into the .308 magazine well, and use the front pivot pin on the .308 lower to catch the adapter. Pivot the upper down, push the rear pin, and you’re ready to load 5.56 magazines and get to work. As an added bonus, when the 5.56 upper, with its adapter, is in the .308 lower, the capture pin of the adapter is inside the receiver of the .308 lower. It can’t work its way loose.

A Better Idea
I have to take back a whole host of the snarky, borderline insulting things I’ve said about Colt; this is a beautiful bit of design and engineering. If all you want is a .308 rifle, then you can get one of these and not look back. If you want a rifle that can be either, you get the .308, a Colt upper (they sent me an LE6940 upper to combine with the .308 lower) or any mil-spec 5.56 upper and you have whichever rifle you want that day.

How well does this work? In a word: great. I took the rifles along to an LEO patrol rifle class, and as much as I would have loved to have used the .308 on the computer pop-ups, the range safety fan is too short to permit use of the big one. So I used the 5.56. With the 5.56 upper on the .308 lower, I had to point out to most who handled it that it wasn’t just another 5.56. That’s how well it fits, showing how well Colt integrated the .308 and the 5.56 design. As for shooting, it was easy dropping 300-meter targets with iron sights.

Once back at home, I set up the uppers the way I figured they would most likely be used in an LEO or military context. On the 5.56 upper I installed an ACOG 4×32 ECOS, complete with four-MOA RMR red-dot close-range sight. It nestled right over the Matech iron sight Colt had installed on the LE6940. On the .308 upper I installed a 1.1-8X Leupold CQBSS mounted in a LaRue quick-detachable mount. It, too, fit right over the Colt-installed rear sight, a Colt-labeled Troy Industries folding BUIS.

Were I to be using them for any time, I’d put a two-point sling on, with a QD setup on the front. That way I could swap uppers and be able to unsnap the sling from one upper and reattach it to the other. If you are a fan of lights and lasers, you’ll have to have one for each of the uppers. Well, you could get by swapping a light from one to the other, but with a laser you really will want to have the laser coaxial to the bore, and unless you get lucky you won’t be able to simply swap one back and forth.

Weight, Recoil, Add-Ons
Now, as self-loading .308s go, the Colt is not light or heavy. With the 5.56 on, it does make for a somewhat heavier carbine, but not so much that you’d notice. Really, the days of a 5.56 carbine being right around six pounds are long gone, and the 5.56-converted Colt is under 7½ pounds—in a word, normal. The recoil in 5.56 is unremarkable. In .308 it’s a bit brisk, but well-handled by the extra weight—the bare .308 comes in at just under nine pounds. For those who would be using a .308 in offense or defense, say a police sniper or military designated marksman, the recoil will be mitigated by the light, bipod, laser (AN/PEQ-2A or ATPIAL) and scope attached to it. I can see a rifle easily getting past 12 pounds  so equipped. And at that weight, recoil is not going to be a problem.

Now, don’t get me wrong. There is recoil, and you’ll have to handle it. If you are one of those shooters who takes what I call the “bazooka hold” with a 5.56, one where only the toe of the stock is barely contacting your shoulder above the collar bone, the .308 will make you pay. You have to get the recoil pad down on your body, or your shooting session will be short, painful and fruitless. Hold it properly and you won’t have a problem.

The barrel twist on the .308 is also a matter of interest. At 1:12 it is a bit slower than is customary. However, unless you are hurling heavyweights, this isn’t a problem. As a fellow gunwriter commented, “All a rifle like that will see is 147-grain M80 and 175-grain M118LR, so 1:12 is not a problem.” Well, that and Federal 168-grain Gold Medal Match, the standard load of police marksmen. Out of the .308 case, you really aren’t going to be pushing anything much heavier than the M118LR load.

With a 5.56, it is possible to spend all day at the range and only have to worry about overheating a barrel. With a .308, it’s possible to get tired and beaten up from recoil, at least to the point where your group sizes suffer. So I took it easy. The 104 degrees my portable thermometer was registering encouraged me to split my range time over several days. In all that, the Colt did not let me down. And best of all? The MSRP is astoundingly reasonable, so much so that I’m seriously considering breaking the cardinal rule of gun writing. I may buy this one.


The .308 shot nearly as well as the 5.56, and the difference was probably due to recoil, not the scope, ammo or rifle.

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