Thinking you’re going to get more flexibility from the purchase of a stripped upper receiver instead of a complete upper receiver? You’re probably right. Although complete uppers come with everything you need to pair to a lower and a parts kit, a stripped upper will effectively only contain the “housing” that accepts all of the other parts. Here’s what else you’ll need to assemble a “complete” upper.
Bolt Carrier Group (BCG)
The stripped upper will directly house the bolt carrier group which contains all of the components of the bolt, including the firing pin, extractor, ejector, and gas rings. You can choose a simple black phosphate mil-spec BCG or a modern, advanced BCG enhanced with a special nitride or nickel-boron coating that is harder, easier to clean, and exhibits superior permanent dry lubricity.
Charging Handle (CH)
The charging handle is used to manually cycle the action, either to load the first round into the chamber or to clear a jam. Some charging handles are ambidextrous and port gas away from the user.
(One note: some completed uppers may specifically be listed as “No BCG or No CH” which means that they do not come with a bolt carrier group or charging handle, so be aware of this if you are interested in purchasing a complete upper instead.)
Ejection Port Door and Forward Assist
Many stripped uppers do not come with ejection port doors or forward assists, so you’ll need to purchase these piecemeal if you don’t take the complete or assembled upper route.
Barrels are not only caliber-specific but also come in a variety of lengths and finishes in order to suit demand. Many AR barrels are given what is called a CMV or Chromoly Vanadium finish, which is highly corrosion resistant – a big bonus for an AR. Also, look for higher rates of twist, like 1:8 as higher rates of twist are better for spin stabilizing thinner, faster projectiles.
You’ll also need a handguard to protect your barrel, protect your hands, dissipate heat and provide options for mounting accessories. Many popular models are classic Picatinny quad rail handguards, but modern options include KeyMod and M-LOK handguards that are lighter, thinner, and provide excellent recoil resistance to mounted accessories like lights, scopes, and other optics.
Gas System (Gas Tube and Gas Block)
The gas block connects to the gas journal over the barrel and the gas block directs gas from the barrel to the gas key of the bolt carrier group. Make sure you select a tube that fits your barrel and a block that fits your gas journal. You should also give preference to low-profile gas blocks as these offer greater clearance under modern, thin handguards.
Learn More at 5D Tactical
Thinking about tackling your home build with a stripper AR-15 upper receiver assembly or an upper assembly? 5D Tactical (5DTactical.com) has both complete uppers and stripped uppers, including billet uppers and mil-spec, forged uppers. They also carry all of the components mentioned here, along with complete build kits, lower receiver blanks, and 80% lower jig kits.