Building with an assembled upper offers plenty of benefits over building with a stripped upper and buying all of the other parts piecemeal.
It saves time, energy, and potentially money, and on top of that, guarantees that all the parts will be compatible and work together well.
Still, you want to know what you’re getting, so here are some high-level things to consider with each of the main upper components.
The Barrel
When evaluating a barrel, consider:
- Length: Barrels that are longer will be heavier and may not be as suitable in close-quarters engagements, but they will also produce more muzzle velocity as they give the bullet more time to accelerate.
- Steel: The steel alloy from which the barrel is made will impact its suitability as well as its corrosion resistance. Many modern AR barrels are made from corrosion-resistant CMV alloys.
- Finish: AR barrels are usually treated with a finish, either nitride or parkerized (phosphate) both of which are resistant to wear and corrosion, though other finishes exist.
- Rate of twist: The rate of twist of a barrel impacts how well it will stabilize a bullet in flight. Most 5.56/.223 barrels have rates of twist between 1:7 and 1:10, but different calibers need different rates of twist.
The Muzzle Device
Most assembled uppers will come with a muzzle device, but understanding what each muzzle device does is important.
- Muzzle brakes: A muzzle brake is a muzzle device that changes how gasses are ported at the muzzle, with the intended effect of cutting felt recoil and muzzle flip, in some cases by as much as 50% without adversely affecting shot power.
- Tuners: Some barrels are equipped with tuners, which help tune barrel harmonics, to help eliminate barrel whip, which can adversely affect accuracy.
- Flash suppressors: A flash suppressor is a basic muzzle device that helps obstruct muzzle flash, which helps prevent obstructing the shooter’s sight picture.
An assembled upper might also be outfitted with a pinned or welded suppressor, which is a muzzle device that makes the gun quieter. A suppressor will also add length and weight to a barrel. In addition, suppressors add muzzle velocity, cut recoil and muzzle flip, and can obstruct muzzle flash.
Important note: if your barrel is threaded but for some reason does not come with a muzzle device, always keep a thread protector installed to prevent damage to the threads.
The Bolt Carrier Group
The main thing to consider with your choice of a bolt carrier group is the coating. The mil-spec standard for BCG coating is a phosphate coating, which is a durable, corrosion-resistant coating with a bit of a tooth. More liquid lubricant is necessary with this type of coating.
There are also hard chrome coatings, as well as a variety of modern coatings, such as nickel boron, black nitride, diamond-like carbon (DLC) and titanium nitride.
All of the latter not only offer excellent corrosion and wear resistance, but they also all exhibit extremely high permanent dry lubricity, which means less liquid lubrication is needed in conjunction with them.
The Handguard
There are three main options you will have with respect to what kind of handguard you want to choose. These are:
- Picatinny rails: Picatinny, or “Pic” rails have been the standard for about 30 years. They are heavy and rough on the hands, but there are many attachments designed with Pic rail mounts.
- M-LOK rail systems: M-LOK rail systems are lighter and easier on the hands than Pic rails, but there are not as many accessories available for them.
- KeyMod rail systems: KeyMod rails, like M-LOK rail systems, are also lighter and more comfortable to grip than Pic rails, but there are also fewer accessories available for them.
In addition to these, you may also come across assembled uppers with tropical style handguards, which do not offer additional mounting points.
The Charging Handle
There’s not much to consider in terms of standard charging handles. The question comes when you want to look for an upgrade. There are lighter, more ergonomic AR-15 charging handles that offer ambidextrous functionality and are easier to use with gloves on. Some of them also help vent gas away from the operator’s face.
Other Upper Components
In addition to these components, you will want to make sure your assembled upper comes with a gas system (usually integral with the barrel), a forward assist and an ejection port cover (also called a dust cover), as well as a barrel nut, to secure the barrel to the upper receiver itself.
Looking for an Assembled Upper? We Have You Covered
In the event you’re here for an assembled upper, we can help you out. Take a look through our collection of complete assembled uppers and get in touch with us at Sales@MCSGearup.com if you have any questions before you buy.