The Colt SP6920 is Colt's primary M4 Carbine clone sold to civilians and law enforcement in the United States. It features a 16in. (40.6cm) barrel to avoid classification as an SBR, and is practically identical to the military's Colt M4 Carbines in every other way, save for the lack of fully-automatic/burst fire modes. While they used to commonly be offered with a rail-mounted carry handle sight, most SP6920s have been sold with a simple flip-up rear sight since most owners swap the carry handle out for an optic of some kind, anyway. The particular SP6920 we'll be looking at today has been outfitted with MagPul furniture, an EOTech holographic sight, a flip-away magnifier, and some other accessories which we'll take a closer look at. Let's go ahead and take a look at the rifle itself, however, from the right-hand side.
As mentioned, here we see the SP6920 with several aftermarket features. As you can see here, beyond the optics set-up, this rifle is pretty basic in its configuration. Here we can get an alright look at the EOTech and flip-away magnifier optic configuration, and we can also see that there is a flip-up rear sight tucked away in case those two optics were to fail. We'll take a closer look at this configuration later, but for now, let's start at the muzzle and work our way back.
The Colt 6920 features a threaded 16.1" barrel, and sitting on those threads is something that about any AR owner is familiar with: the M16A2-style flash suppressor. It does a decent job of acting as a combination flash suppressor/compensator. While not the best at either, it's still good enough for government work.
Further down the barrel, we reach the gas block/front sight block, as well as the bayonet lug and sling swivel on its underside. The 6920 is capable of accepting bayonets, but due to its carbine-length gas system and 16in. barrel (versus the M4's 14.5in. barrel), they don't quite fit properly on the rifle as the bayonet ring sits too far back on the barrel rather than resting on the muzzle device.
Here is a bit better look at the front sight block. It is the standard 'A2-style, fixed front sight. Due to the optics on this rifle, we'll go ahead and just take a look at the front sight now.
The front sight post is capable of being rotated up or down in its position in the front sight block. To rotate the sight post, you'd depress the little button at the front of it, then rotate. You can use a bullet tip or a small punch. Each click/quarter rotation corresponds to approx. 1.4MOA adjustment in elevation.
Next we see the Foliage Green MagPul MOE handguard. This handguard is pretty lightweight, and does a decent job at heat dissipation. The little slots you see in it double as Picatinny rail attachment points (or MOE-style accessory attachment points), and also as a cooling feature of sorts as air can get to the outside of the barrel a little bit easier.
Further back we see the ejection port and bolt-carrier. In this photo, the spring-loaded dust cover is down. This cover can be pressed up to close the ejection port, preventing debris from entering. As soon as the bolt moves upon being fired (or released if you closed it on an open bolt), the dust cover goes down to allow for the ejection of the casing.
Directly underneath this area is the magazine release button. It can easily be reached with the firing hand's trigger finger if right-handed. Depressing it causes the inserted magazine to fall free of the rifle.
Here we see no ammunition is present in the magazine. You'll also notice that this particular magazine has had a MagPul follower placed inside it.
At the rear of the upper receiver, you will see the rifle's ambidextrous charging handle. The charging handle features a small "claw" of sorts on the left-hand side, however, as you'll see here.
To manipulate the charging handle, you will need to pull back on either side of it with your fingers. The finger on the left-hand side will rotate the securing claw of the charging handle outwards, as to free it from the receiver.
Go ahead and pull the charging handle rearwards. If you were to be chambering a round into the rifle, you would pull this handle as far back as possible, and then let go of it, allowing it to slam forward under the force of the bolt-carrier and the buffer tube spring. However, we're going to hold the bolt open for the purposes of this review, so hold the charging handle back by-hand for just a second.
While holding the handle back, I am going to go ahead and pull out on the bolt-catch/bolt-release button on the left-hand side of the lower receiver (alternatively, you can simply press in on the lowest portion of this lever to angle it outward as it is much easier). When the AR-15 fires the last round in the magazine, the magazine follower presses this lever up and outwards, holding the bolt to the rear. Basically, what we're doing here is replicating that function with no magazine present. If you were to insert a magazine into the rifle with the bolt held back, to chamber a round, all you would need to do is push this button in. It would release the bolt, saving you from having to pull the charging handle again.
Here we see the charging handle fully rearward with the bolt and bolt-carrier also held to the rear (you can see into the chamber from here). Note, however, that the charging handle will only be fully rearward if you charge the rifle by-hand. The AR-15's charging handle is non-reciprocating, so when firing, it will not move at all as it is not directly connected to the bolt-carrier.
Here we see the charging handle forward. Note how the bolt and carrier are still held to the rear, however. This is, again, due to the charging handle of the AR-15 being non-reciprocating.
Just below the charging handle on the right-hand side of the upper receiver sits the forward assist. This feature was first introduced on the M16A1 back in the 1960s. Its purpose is to allow the user to manually force the bolt into battery if it were to get caught up just slightly out-of-battery for whatever reason. Since the charging handle is not directly connected to the bolt, that meant that pushing the charging handle would do nothing, thus the forward assist had to be installed. It pushes into the receiver and engages the serrations on the right-hand side of the bolt-carrier, pushing it forward.
On the other side of the rifle, on its lower receiver, sits the selector switch. When the switch is positioned in this fashion, the rifle is on "safe," as indicated.
A quick flick of the thumb, however, and the safety has been rotated 90 degrees. This sets the rifle to "fire," as indicated (some AR-15s have "semi" here). If this were to be a select-fire weapon featuring a burst or full-automatic mode, it would have a third selector position 180 degrees from "safe" for those features.
This particular 6920 also features a MagPul pistol grip that houses an internal storage compartment. Standard M16/M4 grips do not have a trap door on the grip, and are simply hollow. With the MagPul grip, you could store batteries for an optic, lubricant for internal parts, or Skittles for mid-operations refueling.
The buttstock on this 6920 is also of the MagPul variety. It is a "UBR," and is a type of collapsible buttstock. The top half serves as a cheek pad, while the bottom half moves forward or back to adjust length-of-pull.
To adjust this particular stock, all you would need to do is push the tab on the bottom of the stock rearwards towards the but, then slide the stock half in the desired direction. Once this was accomplished, it would lock itself in place and remain in that position until changed once more.
To begin disassembly of the rifle, you'll need to turn your attention to the rear of the lower receiver, left-hand side. There is a take-down pin located just above and behind the selector switch. Press in on it with your finger, with a bullet tip, or with a punch of some kind.
After you've started it out the right-hand side of the receiver, grab a hold of it and pull it completely out to the right until it stops itself (it is a captive pin). Once you've done this, you will have disengaged the receiver halves from one another in a way that allows you to "shotgun" the rifle for maintenance.
I prefer to completely separate the halves, however, so to continue, we'll turn our attention to the forward take-down pin. It is the forward-most thing on the lower receiver. Push it through to the right.
It, too, is a captive pin. Once you've pulled both take-down pins out, you should be looking at something that resembles this. Once you are, go ahead and pull the two receiver halves apart from one another (upper receiver and barrel; lower receiver and stock/grip).
We'll turn our attention to the lower receiver first. There really isn't much to do with it as far as field-stripping goes beyond removing the buffer and spring, so we'll go ahead and do that.
Here we see the buffer. As you can tell, there is a little pin near the bottom of it holding it in place. This pin is spring-loaded. Go ahead and use your thumb or a punch to depress the pin. The buffer will begin to launch itself out of the buffer tube.
Here is the buffer partially out of the buffer tube. As you can see, the buffer spring is snagging a little bit on the spring-loaded pin that was holding the buffer in to begin with.
To remove the buffer and spring, simply grab and pull up and out. You might need to toy with the spring a bit since it likes to snag on the buffer detent pin at the back of the receiver.
Here is the buffer and spring removed from the lower receiver. Next step is to remove the spring from the buffer. It is a fairly easy process.
Grab the buffer and spring and simply pull them apart. It might snag a little bit since the buffer is stepped towards the front, but don't be afraid to twist the spring off of the buffer if needed.
Now we'll turn our attention to the upper receiver. Go ahead and grab a hold of the charging handle once more. We're going to be pulling it rearwards.
Pull the charging handle rearwards, as mentioned above, but not quite all the way just yet. You'll be looking at something resembling this at this point.
Go ahead and grab the bolt-carrier at this point and pull it out the rear of the upper receiver. Since the charging handle is not directly attached to it, as mentioned earlier, it will stay in place.
Here is the bolt and carrier as it appears removed from the rifle. As you can see, it has a cut-out running its length towards the rear: this is to make space for the hammer of the rifle. The large portion in front of it, however, is where the bolt and gas key are housed. We'll take a closer look at those in a second.
Next, grab the charging handle and continue to pull rearwards. It will stop after a while, and once it does, simply lower it slightly and pull it out the rear of the receiver.
Here is the charging handle removed from the upper receiver. As you can tell, it's a pretty simple device. It simply hooks over the gas key, but lets the bolt move freely even while the charging handle remains forward.
We'll go ahead now and begin disassembly of the bolt carrier. The first step is to remove this, the firing pin retaining pin. If your fingers are small enough, you can just grab it and pull. If not, you will want to insert a bullet tip from above and angle it out to where you can grab it with the fingers. During the installation process, you may need to use a punch or bullet tip to keep the "open" end close together, otherwise it will be blocked by the bolt-carrier body.
Once the firing pin retaining pin has been removed, the firing pin can be removed. To remove the firing pin, either "dump" it out of the bolt-carrier or reach in with your finger and pull back on it.
The next step is to remove the cam pin from the bolt-carrier. This is the little rectangular piece under the gas key. It serves the purpose of rotating the bolt into the locked position when chambering a round.
Anyway, to remove it, simply push the bolt back into the bolt-carrier. This will rotate the cam pin down and rearwards, off to the left-hand side of the bolt-carrier, as seen.
Once the cam pin is in this potion, rotate it 90 degrees. This will allow it to clear the gas key when removing it from the bolt-carrier assembly of the rifle.
To remove the cam pin, simply grab it and pull it out of the bolt. Pretty basic stuff. Just remember to do the same, but reversed, when reassembling.
The last part to remove is the bolt. To do so, simply pull forward and out of the bolt-carrier. The extractor's spring tension may cause the bolt to resist being removed a little bit, but you won't damage it by simply tugging a little harder.
Here is the bolt-carrier and bolt completely disassembled for a basic cleaning/field strip. To put the AR back together, simply reverse all steps seen above.
This particular 6920 has not one, but three rear sights. The order we'll be looking at them is from most advanced to most basic. As you'll see here, there is a flip-away 3x magnifier installed on this rifle. Let's take a look at what optic it's sitting behind first before moving on.
The primary optic on this rifle is an EOTech EXPS3. It can have its brightness adjusted, features a night vision setting ("NV"-marked button), and is powered by a single 123 lithium battery (placed perpendicular to the bore).
Here we see the EOTech reticle (1MOA dot in 65MOA circle) as viewed through the 3x magnifier. As you can see, the front sight post is still fairly visible, but does not present a problem as the dot stays on-target, even if the head is not in an ideal firing position. This is due to the EOTech using a holographic reticle.
The 3x magnifier is not always needed, however, so it's good to be able to move it out of the way. Since this one is a flip-away, it means we can leave it installed on the rifle while still getting it out of the way. Simply depress the button near the base of the mount. This frees the hinge, allowing you to rotate the magnifier out to the 3 o'clock position and out of the way.
Here is the EOTech as you'd see it when aiming with the magnifier out of the way. Again, the front sight is easily visible here, but it doesn't matter as the point of impact is going to correspond with the EOTech's 1MOA dot. What happens when the batteries die, however? Let's take a look.
The rear "iron" sight on this 6920 is a polymer, flip-up sight. It is seen here in the folded position, as that is what allows the 3x magnifier to be used, and also obstructs less of the EOTech's sight picture when using the dot. However, in case the battery dies, you can press on this forward portion of the rear sight.
Doing so will free the sight from its lug holding it in the folded position, allowing it to pop up into place. Releasing the button then engages the "unfolded" lug of the sight, holding it in place.
The MPBUIS (MagPul Back-Up Iron Sight) allows for what is known as a lower-1/3 cowitness. This means that you can use the red dot and iron sights at the same time (cowitness), and that, while doing so, you are looking through the lower 1/3rd of the EOTech's lens. Worth noting, the "starburst" effect from this image comes from my camera focusing on the front sight rather than the target/holographic reticle.
What you saw above was the cowitnessed view of the sights with the small aperture. For close-quarters, moving targets, or low-light shooting with the irons, however, another aperture is available. Folding the MPBUIS aperture down allows you to use this second, enlarged aperture.
Here is a view down the cowitnessed sights of the 6920 while using the larger aperture. As you can tell, it's not quite as precise, but you get a much more open sight picture. This means more light is reaching the eye (allowing better vision when aiming in low-light), and more of the target is visible while aiming. That will come in handy on moving targets or close-up targets where precision is not the biggest concern. Again, the holographic reticle has been distorted due to focusing on the front sight post rather than the target/reticle itself.
So, there you have it: the Colt 6920, and several of its available aftermarket accessories. While the sight system is a bit overkill for some folks, I can see why others would appreciate the ability to have multiple options. However, it does come at the cost of added weight to an otherwise light rifle, and the deployed 3x magnifier can be a bit of a burden when trying to grasp the charging handle. These rifles are pretty nice, however, and are definitely a great first choice for an AR-15 if you're not too sure what direction you wish to go with it: they're a jack-of-all-trades, off-the-shelf rifle, basically. Not necessarily perfect at any one task, but capable of being used for several effectively enough.