Getting the Right AR Upper
Here on this site, we talk a lot about lower receivers, and 80% lowers in particular because, if you are building your custom AR, that is where you tend to start, and all other parts build up onto it.
We don’t, frankly, give enough air time to upper receivers, but these can be just as important, and not only because they form the other side of the receiver assembly. While it is the lower receiver that is considered the “firearm”, and therefore gets both a lot of attention and usually (though not exclusively) a serial number, the components that most largely determine the performance of the rifle all reside with the upper receiver. The upper contains the bolt carrier group, and is the half of the AR15 (or AR10) that the actual barrel attaches to, so making the right selection of upper parts to how you intend to use the rifle becomes very important.
Materials and Forms
Like lower receivers, uppers can be purchased in a range of materials and manufacturing conditions. The options for forms are pretty much the same as for lower receivers – forged, billet or cast. Forged will always be the strongest and most dependable, but you’ll pay the highest price for them and you probably only need to consider them if you are planning sustained firing modes or very heavy calibers – probably from .308 upwards.
Next comes uppers machined from billet material, which is a halfway house between cost and performance. If the idea of putting rounds through a cast material upper fills you with a little disquiet, then go for a billet. Finally, the cheap option is cast and these are fine for smaller, less punchy rounds, and are a great way to start tinkering with your AR as a project.
While your upper is essentially a chunk of machined metal, there are different variations on the market as to how you can get it as an assembly. These are:
- Stripped Upper
Basically, just the upper, which may be in a state where other parts will need to be added to complete it.
- Assembled Upper
This comes complete with all relevant parts such the ejection-port door and the forward assist installed.
- Barrelled Upper
This includes the upper receiver barrel, handguard, gas block, and gas tube fitted into place. Barrelled uppers generally don’t include the carrier group or charging handle
- Complete Upper
This assembly contains all parts discussed as well as the bolt carrier group and the charging handle and is essentially ready to go straight onto the lower receiver to form the finished gun. Many complete uppers may be supplied with ancillary items such as iron sights too.
The main difference between these variants is price and the amount of work needed to use them. If you are on a tight budget, you may decide on a stripped upper and then carry out all of the work assembling it yourself, whereas if you have the money, and don’t fancy doing the work, a complete upper may be for you.
This is going to be the main driver behind your choice of upper receiver. The upper dictates the barrel and caliber that you are going to use, so you need to consider what you are building your AR to do. If you want a good hunting round like a .308, then that is what you will build your upper to chamber, and likewise with other calibers. However, all is not lost if you want to use other calibers, but it may mean that you have to hold onto a range of assembled uppers and barrels for each caliber of your choice. You can swap their out pretty quickly and be ready with a rifle that suits the circumstances.
Because your upper is made of aluminum alloy – regardless of whether it is forged, billet or cast – it is also capable of being anodized to give it a strong, quality finish. And of course, as well as being hard wearing, anodizing is available in just about any color you like, so if you are really customizing your AR, you are bound to get something that suits you perfectly. In addition, there are companies who manufacture upper and apply different finishes, such as a nickel boron coating, which is similar to the coatings that are popular on internal AR components. As well as giving a unique looking finish, they also offer excellent wear and corrosion resistance, but do tend to be a tad more expensive.
The modular design of the AR rifle means that you can pretty much tinker around with all the parts, including the upper receiver. Whether you are planning an AR15 or an AR10, you will enhance your weapon by getting the right upper receiver for the job.