The AR-15 is instantly recognizable by its distinctive, traditional upper receiver profile. However, time marches on and the only thing that remains the same is the fact that things change. The AR-15 has gone through numerous evolutions in its military application as well as adapting to the demands of the civilian market.
Many AR-15 upper receivers seen today bear little resemblance to the original military issue M16A1 that began its service during the Vietnam conflict. While the weapons design differences may appear to be cosmetic they are indeed not. By adding or taking away features to the upper receiver, the function and purpose of the overall weapon are fundamentally different. Whether these changes are welcomed or scorned depends upon individual needs, tastes, and use of the weapon.
AR-15 Upper Receivers at A Glance
Regardless of configuration, all AR-15 uppers perform the same basic job. At its heart, all it must do is contain the bolt carrier group, charging handle, facilitate a means to close the action manually, and cycle the action when it’s fired.
Of course, there is stress imposed on the upper when a round is fired, but the force is focused more in the bolt carrier group and buffer system. The structural integrity of the upper receiver is important, however, a quality upper is likely to outlast its internal components.
Forward Assist, Tradition or Folly
An AR upper receiver houses the traditional forward assist button by which many people identify the AR-15, falsely believing it’s not a real AR-15 without one. In fact, the first AR-15s that were delivered to the military did not have the forward assist installed as an option. The military subsequently required that the forward assist was added before the full rollout of the weapon to the infantry. This feature does indeed serve a purpose, however, many shooters misunderstand its use.
The notion of using the forward assist button to ram home a shell that doesn’t fully seat can result in a dangerous situation for the shooter. First, there could be an issue with the round itself in regards to its overall length or brass that is out of tolerance. Either way, that cartridge doesn’t belong in the chamber and forcing it in could create unsafe chamber pressures upon firing. Second, contamination in the form of carbon build-up or debris could be present on the bolt face or in the chamber of the gun. Again, that issue must be resolved in order to safely load and fire the weapon. In either situation, one certainly should address the underlying problem and not simply shove the round into the chamber.
Where the forward assist truly comes into play is by facilitating the silent chambering of a round. When you cycle the charging handle, spring tension slams the action closed. Unfortunately, this comes with a certain degree of noise. In a combat setting the sound of an entire platoon working their charging handles could easily be detrimental to their health. This is where the forward assist comes into play. The shooter is able to ease the action shut slowly and quietly. If the round doesn’t fully come into battery, a slight push of the forward assist button will bring it in with a slight click. This is not only a benefit in combat, this feature could easily be a big help for loading the weapon during a hunt without alarming one's prey.
Things Change And Still Stay The Same
Throughout every generation of the AR-15, the main visual difference is the disappearance of the once prominent carry handle atop the upper receiver. Although, this feature was the mounting point for the rear sight and carrying the gun by the rear sight mount may not be the wisest choice, so the term carry handle is a bit of a misnomer. Normally when the carry handle goes away, a Picatinny rail appears on the flat top upper. Picatinny rails provide a stable mounting surface for iron sights, optics, or other accessories. Still, the AR upper receiver has retained its modular design.
This is perhaps its greatest selling point. All that needs to happen to transplant an AR upper onto another lower is the removal of its takedown and pivot pins. With another complete AR upper receiver standing by, an entirely different weapon is at the ready in minutes.
The AR-15, chambered for 5.56, utilizes a smaller framed receiver set. Therefore, just about any shorter profiled round can safely run through its action. The most popular change is from the 5.56 to the .300 Blackout. This combination uses all of the same parts except the barrel to create a whole new gun. One can literally have an entire arsenal ranging from a .22 LR all the way to a .50 caliber Beowulf at your disposal. If the cartridge is based on the .223 the change required is minimal, others will require a different bolt carrier group and magazine.
Stripped Down or Dressed Out
All AR-15 upper receivers can be bought in one of three levels of completion. Depending on one’s level of expertise, spare parts available, and individual preference deciding which upper to get is very easy.
- Stripped Upper Receiver: Stripped AR-15 upper receivers are by definition exactly what the name implies. You get an empty shell that must be fitted with all the parts necessary to make it a fully functional upper receiver. This is a good starting point if you have the parts on hand to complete the build or have a particular bolt carrier group in mind.
- Assembled Upper Receiver: An upper is considered “Assembled” when it is endowed with an ejection port door and forward assist button in place.
- Complete Upper Assembly: This category provides everything including a barrel and gas system and is ready to attach to a lower and fire.
M4 Feed Ramp Mania
Here of late many manufacturers, as well as shooters, have praised the fact that now M4 feed ramps are everywhere. Is that a good thing? Well yes, it is but is it necessary, now that’s another question entirely. Answering that question requires a look into why the M4 feed ramp was created in the first place.
We all know that the M4 is the shorter version of the M16 designed primarily for special forces and delivering automatic fire when needed. Early feeding issues in the M4 necessitated a modification in the upper receiver and barrel extension. Longer feed ramps were machined into both surfaces, therefore, providing a more gradual transition from magazine to chamber. Voila, the M4 feed ramp was born, and it did indeed solve the feed issues the M4 had during automatic fire. But, are they necessary on a semi-auto gun? Again, the answer is it depends on what you have to start with.
Basically, the upper receiver should match the barrel where M4 feed ramps are concerned. The extended feed ramps can be present in both the upper as well as the barrel and therein lies the potential for failure. If the upper receiver has M4 ramps and the barrel does not, this creates a situation where ammo will most certainly hang up when feeding. Conversely, if the modified ramps are present on the barrel but not the upper then feeding will not be a problem because the bullet has nothing on which to snag en-route to the chamber.
If the build is to be made up of new parts this likely will not be a problem seeing as how most manufacturers now install M4 feed ramps on everything. However, in keeping with that old “ounce of prevention” rule, please do take a minute and make sure of what you’re working with.
There are three different methods for manufacturing AR-15 upper receivers, billet, forged, and cast. While they all turn out a similar product, the process is quite dissimilar.
Billet AR Upper
Billet is a general term meaning, in this case, to take a solid chunk of aluminum and mill away everything that doesn’t look like an upper. These are considered a “one-off” part and the extensive machine time causes a subsequent rise in cost. Even though a CNC milling machine does the work, billet uppers cannot be considered a mass-produced part.
A billet AR upper usually has thicker walls when compared to a forged upper receiver. The ensuing part is usually not considered to be a Mil-Spec AR-15 upper receiver and may have some issues when fitted to a Mil-Spec lower. However, when one gets both a billet AR upper and lower machined as a set the fit is normally precise and produces a more stable accurate gun. This is a benefit if one is going for a long-range precision gun. An AR-15 billet upper receiver is considered the gold standard for top of the line custom builds.
When shopping for stripped AR-15 upper receivers, the billet option is prevalent throughout the market. The finish of an AR-15 billet upper receiver is going to be cleaner and have sharper details than its forged AR-15 upper receiver rival.
Due to its thicker walls and greater rigidity, an AR-15 billet upper receiver would be a better choice if the gun is to be fully dressed, suppressed, and running hot loads. The billet AR upper will withstand this added stress better than a forged upper receiver.
Forged AR-15 Upper Receiver
When looking for an AR-15 upper receiver for sale perhaps the best value for the average shooter can be found with a forged upper receiver. These uppers are made by heating the aluminum to a temperature between 800 and 900 degrees, then hammer forging it into a die. This results in a part that is nearly a Mil-Spec AR-15 upper receiver. It is then machined to its final stage using a CNC mill.
While the initial outlay for dies and tooling is considerable, the procedure for creating a forged AR-15 upper receiver negates much of the costly machine time. Therefore, multiple parts can be mass produced with a minimum of wasted material and time, resulting in a lower overall cost per unit.
When comparing billet vs forged receivers, it’s like comparing apples to oranges. Each one has its place and market following. Even though normally a billet AR upper has a superior finish one cannot automatically declare the forged upper receiver to be inferior. The quality of finish in every case depends on the final machine work and the individual executing it.
The forged AR-15 upper receiver was ordained by the military for use in all of their AR framed guns. It is doubtful that any gun is going to see more severe abuse at the range than it would in combat.
Cast Upper Receiver
The process of casting is quite old and consists of pouring molten material into a predesigned mold to produce a part. Commonly referred to as “die-casting” this is the same process used in making hot wheel type toy cars. This procedure is used primarily to make lower receivers and very few companies attempt to employ it to make uppers.
Casting produces parts that are considered to be brittle and the least resilient of all three methods of manufacture. In most cases, the cost of a forged upper receiver is low enough to not even consider the option of one that is cast.
When looking at a new AR-15 upper receiver for sale you have the opportunity to adapt your weapon to your specific needs. The addition or subtraction of the forward assist, brass deflector and Picatinny rail is all customizable as per your preference.
By simply changing the upper, that tack-driving varmint gun can become a close quarter battle weapon in minutes. If perhaps, your lower has a high-end trigger and stock that you love, you can keep the familiar set-up and just switch the upper to fit the new need.
The original gas impingement system on the AR-15 can even be changed over to a piston driven action if you so desire. The piston driven action is considered by many to be more reliable and run much cleaner.
So Many Choices
The selection can be daunting unless it is broken down into a logical process. The first consideration is billet vs forged, this choice is mainly price and purpose. Casual shooters will save a bit by going to the forged option while high-end competitors requiring more precision would likely lean toward the billet designed receiver.
A “slick” upper without a forward assist or ejection port door is a bit lighter and would lend itself nicely to long-range competition and varmint shooting due to its minimal profile. Conversely, if you stay in the brush or are into the grip and rip three-gun competition, then those accouterments would be a benefit. In dusty environments, an ejection port door will protect those expensive internal parts while a forward assist will enable you to quietly chamber a round.
Whether to get a stripped down or a complete upper receiver honestly depends on your level of comfort in building one on your own. Usually, the cost of a complete upper is a bit less than buying all the individual pieces and putting it together. However, in doing so you are at the mercy of a premade combination which may not be the best for your needs.
Unless the goal of your build is an ultra-light platform, weight shouldn’t even come into the equation. The difference of an ounce or two between upper receivers is negligible. Additionally, this weight is in the center mass of the gun and not hanging off the end.
Another point is has the upper been lapped to achieve true barrel alignment? When the barrel is attached to the upper if the mated surfaces are off even a few thousandths it can cause the rounds to stray. To lap an upper receiver is neither difficult or expensive, however, it is an additional expense if not already done from the factory. This will not increase the accuracy of a weapon but it will certainly improve consistency which is critical for success.
Most shooters gravitate to the flat top style upper simply because of versatility. A common Picatinny rail gives ample space to mount sights or optics. The lower profile yields a more natural position when trying to acquire a target making initial as well as follow-up shots faster.
Adding a brass deflector may seem an insignificant choice, however, hot brass will get your attention. Occasionally, the need to shoot left-handed may arise or your buddy could be just a bit too close. It’s about that time when that silly little brass deflector suddenly grows in importance.
Time to Build That Arsenal
So, all that being said the only question that should remain is which caliber should I choose. All of us are not fortunate enough to go out and buy a new gun to fill a specific need. However, you can add another upper receiver and gain the use of another weapon at a fraction of the cost. Then, as finances allow fitting lowers to them one at a time is a means to add to your collection without breaking the bank.
A great place to find an AR-15 upper receiver for sale is right here at Wing Tactical. We offer stellar customer service and as always a 30-day no hassle return policy. Send us an email, no question will go unanswered and the quality of the parts we offer is impeccable. We will not rest until you find the AR-15 upper receiver you need.
We sell the following uppers:
- Seekin Precision NX15 Upper Receiver: One of the industry’s best upper receivers, the Billet Upper Receiver is composed of aircraft-grade aluminum. Made with some of the most precise CNC processes that exist, this upper is sure to meet your needs – and then some. It's Skeletonized design removes excess weight and material. This upper provides the perfect foundation for an optimal shooting experience.
- Aero Precision Mil-Spec AR-15 Upper Receiver: The upper receiver is a decisive point on your AR 15, and this upper is no joke. Sturdy, reliability and dependable, this upper is machined from strong aluminum. What’s more, it features machined M4 feed ramps that improve the upper’s reliability. We’re confident that this piece of equipment will improve the accuracy of your shots, as it functions flawlessly and gives your rifle a great foundation.