My local gun store has a large selection of guns for sale, and about 10 years ago I remember looking through the display cases and seeing a new Colt 1911 for sale.
“So they do still sell to civilians,” I said to the clerk. My surprise stemmed from the fact that for the better part of 20 years, Colt has nearly ignored the commercial market in favor of law enforcement and military contracts, and finding a new Colt AR-15 sometimes took quite a bit of work.
Colt has changed its strategy, and last year it started a push to reestablish itself in the commercial marketplace. While quality has never been an issue with Colt products, one look at its previous catalogs showed a lack of imagination in terms of gun design. So it was a pleasant surprise to discover the new Colt 901, a convertible .308/5.56 AR.
The parent rifle is officially dubbed the LE901-16s, a 16.1-inch barreled AR-10-styled .308 with a 1:12 twist and a quad-rail fore-end. Colt could have just stopped at offering a caliber-convertible AR, and everybody would have been happy, but it didn’t.
The .308 LE901 comes with flip-up iron sights, an ambidextrous bolt release, ambidextrous magazine release, Vltor IMod collapsible compartment stock with rubber buttpad, two QD sling swivels, rubber quad rail covers and two 20-round Magpul magazines. Not only that, the top and sides of the fore-end are one piece with the upper receiver, machined from a single forging. The bottom section of the rail is attached to the fore-end, not the barrel, which means the barrel is free-floating.
While the fore-end has a rather traditional quad-rail look, albeit with angled cutouts for weight saving and barrel cooling, most quad rails are rough and will chew up your support hand. The 901’s fore-end did not have any sharp edges, and I wonder if perhaps it went through a brief bead-blasting to prevent users from donating blood.
Even without the capability of accepting 5.56 uppers, the .308 LE901 is deserving of respect in its own right. This is a true Stoner-type rifle, otherwise known as a direct gas impingement system. With a legal-minimum 16.1-inch barrel, the LE901 is obviously not intended to be a target rifle but rather a big-bore battle rifle for those jobs or consumers who feel the 5.56 is just not enough. The barrel is tipped with a Vortex flash hider, the current standard for flash suppression.
At eight pounds, 14 ounces empty, the LE901 is neither the lightest AR-10 type rifle you’ll find nor the heaviest, although it may seem heavy compared to a 5.56mm M4. Trust me, when you start touching off rounds, you’ll appreciate the extra weight.
The rear of the lower receiver has the same dimensions as a 5.56 AR, so any aftermarket triggers or grips you prefer will fit. As the trigger provided on the LE901 is pure mil-spec (seven pounds and gritty), I’m assuming a lot of buyers will swap it out for aftermarket models. Forward of the trigger is where you’ll find the really interesting aspects of this rifle.
Colt engineers had in mind at the start to make this a caliber-convertible rifle, so they had to put on their thinking caps when it came time to designing controls that would work whether the magazine well was filled with a .308 or 5.56 magazine. For the record, when wearing a 5.56 top end, Colt provides a magazine well insert to fill the .308-size cavern of the lower receiver, but more on that nifty converta-widget later.
The 901 has both standard AR controls in addition to the ambidextrous ones, so you won’t have to learn a new manual of arms to work it. However, if you’re a lefty, you’ll want to send Colt’s engineers a box of chocolates because the ambi controls are very intuitive and work well.
The ambi magazine release is on the left side of the gun, just behind the magazine well at trigger level. It doesn’t protrude at all, but if you’re a lefty, hitting it with your trigger finger is easy. Empty .308 magazines drop free, even though they are snug enough not to rattle in the mag well. If you shoot right-handed and are accustomed to AK-style controls, hitting the ambi mag release with your left thumb as you strip out the magazine will be second nature.
The ambi bolt release is a big paddle on the right side of the receiver above the trigger. It is moved backward to avoid the ejection port cover. If you’ve got very big hands you might be able to hit it with the thumb of your firing hand (shooting lefty), but otherwise you’ll be using the thumb of your right hand after you shove a new mag in.
Designing this rifle to take SR-25 pattern Magpul magazines was a very smart move. They are widely available and, more importantly, have proven themselves to be reliable.
Accuracy of the 901 was acceptable and hovered around two m.o.a. with most ammo types. For what this rifle is, and what it’s designed to do, that’s plenty accurate. The flip-up sights were rugged and locked in place, but for accuracy work I topped the rifle with a Burris 4.5-14X MTAC scope in a LaRue SPR 1.5 mount. This scope has a nice duplex mil-dot reticle along with good glass and holds its zero. Best of all you can find it online for under $550.
Colt is not the first company to make a caliber-convertible AR, but it is the biggest name to do so. While the rifle will get attention just because of name recognition alone, I have tested and examined other “presto-chango” ARs, and the Colt design is as good as any of them and simpler in design than most. Simple is good. Simple means fewer things to break or go wrong.
Colt sent me a LE6920CK upper for this article, but the beauty of the Colt switcheroo design is that the 901 lower will take any standard .223/5.56 AR top end. Just because somebody says something doesn’t make it so, however, so to verify that claim I spent some time in my basement swapping out uppers on the 901 lower. Yep, every 5.56 upper I had on hand—BCM, Bushmaster, Alexander Arms—fit on the 901 lower.
To see how simple the upper receiver switch was, and to reaffirm my masculinity, I decided to try it the first time without looking at any instructions (I’ve heard it said instruction manuals are just another man’s opinion.)
My exact words during the process, which took all of about 30 seconds, were, “OK, that goes in this way, but where does….oh, wow, that’s nifty. And simple!”
The magazine well insert that allows you to mount a 5.56 top end on the 901 attaches to the front receiver pivot pin hole of the top end, using a captured flush pin of its own. Once that’s attached, just drop the upper onto the 901 lower and push the front and rear receiver pins into place.
That’s it, at least when it comes to swapping out upper receiver assemblies. The process requires no tools, and if you know how to take apart the upper and lower receiver of an AR-15, you can handle this. It is beautiful in its simplicity and can’t work loose or break. Shoving an AR-15 magazine into that big maw of a mag well with the insert in it is a bit like using an AR-15 with a flared magazine well, but the magazines lock up nice and tight like they should.
Before you slap on a 5.56 upper, however, you’ll want to replace the .308 buffer and spring installed in the 901. If you’ve never removed one of them, once you’ve taken off the upper receiver all it takes is the equivalent of a flat-head screwdriver to push down the buffer retaining pin at the inside rear of the receiver. The buffer and spring will then pop out.
Colt provides a 5.56 buffer and spring with the 901, so you won’t have to buy any extra parts. You won’t have any difficulty telling the two sets of buffers and springs apart: Not only are both the .308 buffer and spring noticeably beefier, the .308 buffer is marked “.308.” The 5.56 buffer supplied with the 901 was marked with an H, indicating that it is a heavy carbine buffer.
Say you’re having a bad day and you swap out uppers and head to the range, but you forget to switch out the .308 buffer and spring for the 5.56 ones. What will happen? That’s the beauty of this system; you won’t blow up your gun.
What you will do is turn your semiauto into a bolt action, as the recoil impulse from .223/5.56 won’t be enough to cycle the bolt against that heavy .308 buffer and spring. Going back the other direction (.308 gun with a 5.56 buffer/spring), you’ll have some wear issues if you fire enough rounds, but I’m guessing before that happened you’d find yourself wondering, “Why the heck is this kicking so much?”—then slap yourself on the forehead.
With the 901 lower on a 5.56 upper, you’ll notice the front of the lower receiver sticks out a little farther than usual to accommodate the relocated pivot pin, but other than that it will look more or less normal from a distance. I’m not sure it doesn’t result in a product-improved AR-15, though, between the ambidextrous controls and what in effect is a slightly flared magazine well.
The beefier lower receiver adds only a few ounces when compared to a standard AR-15, and it is in the middle of the gun where you won’t notice it much at all. The weight of the rifle with the Colt 6920 upper installed (a 16-inch flattop M4-type upper with plastic handguards and flip-up rear sight) was just over seven pounds.
For those of you who know how an AR works, you may be wondering how the two different uppers can work with the same buffer tube. Easy—the back half of the .308’s bolt carrier is narrowed down to the diameter of a standard 5.56 carrier. Like I said, simple is good.
The suggested retail of the LE901-16S is $2,129. If you’ve checked out prices of AR-10 type rifles lately, you’ll know that makes the Colt neither the most expensive nor the cheapest. However, purchasing this particular Colt gives you not just a great .308 rifle but, in effect, another 5.56 AR-15 lower with ambidextrous controls, too. Kudos to Colt.