An AR-15 rifle can be divided into two parts: the upper and the lower receivers. Understanding the components of the upper and lower receivers, respectively, is vital to leverage the complete utility of your rifle.

In a two-piece rifle, the upper contains the barrel and the bolt, and the lower contains the fire control group, the pistol grip as well as the magazine. Usually, the lower part of the rifle is one which is registered with the federal agencies, and the upper can be changed at the rifle user’s convenience. Hence, it makes sense to learn more about AR uppers before visiting daniel defense upper.

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Which AR Rifle Upper Gives You The Best Features

The AR upper is where a lot of additions, like the gas block or the modular lock, are installed. The modular lock, or M LOK as it is popularly known, is used to attach lights, lasers, and eyepieces to the rifle. So if you want to add special features to your rifle, understanding the upper and its features is essential.

1. The M4A1 R111 URG Upper


The carbine for this make is M4 type. All special operation units, including the Army Special Forces and the Navy SEALS, use the M4 type. This type of carbine has an effective range of five to six hundred meters. The M4A1 has a heavy barrel, and it can fire almost six thousand rounds before any kind of replacement is needed.

The R111 stands for the rail system of the rifle. The R111 rail system is made up of aluminum. It is one the toughest rail systems that you can come across in the market today. The best part of the R111 rail is that it has the M LOK system instead of the Picatinny rail. The new modular locking does what the Picatinny rail did, but it is way more efficient and useful to work with.

The modular lock has an oblong shape and runs along the entire length of a handguard. M LOK systems allow greater airflow around the barrel of the rifle. When there is greater space for the air to flow, it allows heat dissipation. Also, it is much more lightweight than the Picatinny rail. So the rifle’s overall weight is reduced, making it easier to carry and use.

The biggest advantage of the modular lock system is that it is a free float system. This essentially means that no part of the handguard makes direct contact with the barrel or receiver. As there is no direct contact with the barrel, the M LOK rails do not get affected by the movement of the barrel.

And finally, you can use the modular lock system to mount any length of Picatinny rail onto the rifle. So even if you have the new M LOK system, it does not restrict you from using any old accessory (that was suited to the old Picatinny rails) on your gun.

Apart from the rails and the barrel side, you must also consider the URG or the upper receiver group when buying the upper of a rifle. The URG has a key role in the gun’s accuracy.

The bolt carrier group of the BCG is part of the gun, which helps in semi-automatic firing once the trigger has been pulled. The M4A1 R111 URG is upper and has an M16 profile BCG and Chrome lined bolt carrier group.

2. The DD4 R111 S URG FDE Upper


Just like the M4a1 R111 URG, this model also has an M LOK system, making the rifle lightweight, versatile, and easy to handle. The bolt carrier group of the BCG has an M16 profile and is lined with Chromium.

The gas system uses a part of the gas used to fire the cartridge to insert a new cartridge. Thus, in a way, the gas system provides the energy that is required to operate a locked-breech system. The gas system is a Pinned Low Profile Gas Block that allows for direct impingement.

Apart from this, all the sights that can be fitted into the rails are available separately, and this upper also comes with a heavy-duty stainless steel made charging handle. And finally, the color of this upper is FDE, the FDE is nothing but the greenish-brown color of the gun, which somewhat resembles the color khaki.

3. The 300 Blackout Upper


This rifle upper is great for those who want high performance. The barrel of the rifle is short, and the bolt and magazine are so designed that they can deliver zero-point three-caliber bullets with great muzzle energy. The barrel is ten point three inches long and made up of an alloy of vanadium molybdenum and stainless steel to give the necessary mechanical strength.

The upper receiver of this make is anodized, which gives it the necessary strength and protection against wear and tear. The handguard of the Blackout Upper has four Picatinny rails so that you can attach any mount like sights, lights, and lasers whichever you want. The availability of four Picatinny rails allows for a good amount of customization; hence, this model is quite a favorite for gun enthusiasts.

Though some people may not be comfortable with the use of Picatinny rails yet the Blackout Upper does offer a few distinctive advantages. One of the biggest advantages of the upper is its compactness. The small size of the barrel makes it easy to carry the gun and maneuver it out at the user’s convenience. This compact size makes this upper an excellent choice for those who want to carry a gun for self-defense.


The gun uppers do not have a license, but they are highly valuable when it comes to customization. The mounting system allows for the addition of sights, and the barrel size determines the weight and compactness. Thus, when you set out to buy a rifle upper, do pay attention to the rails, the barrel, the bolt carrier, and the gas system of the rifle. If you do need a lower receiver to go with your upper, visit this website.