Improve Your Component Knowledge of AR-15 Build Kits

Have you begun exploring AR-15 build kits and quickly needed clarification with some of the terminologies? Novice users may need help with unfamiliar words and phrases and feel lost or bewildered. Let?s examine some popular component names and phrases you may encounter when shopping for AR-15 build kits. 

Upper Receiver Group

The upper receiver is the top portion of your AR-15 build kit that contains the barrel, forend, bolt carrier group, charging handle, and any AR accessories you want to mount on rails, like a scope. The upper receiver attaches to the lower receiver to form the complete weapon assembly. 

Lower Receiver Group

The lower receiver is the bottom portion of your rifle, including the fire control group, magazine well, and pistol grip. This section includes the lower parts kit, trigger, buffer kit, magazine, buttstock, pistol grip, safety selector, and bolt catch. 

Muzzle Brakes/Compensators 

Muzzle brakes and compensators have similar functions in expelling gasses from the barrel to reduce recoil and muzzle movement. Muzzle brakes reduce recoil (horizontal movement), while compensators mainly reduce muzzle movement (vertical movement).  

Charging Handles 

An AR-15 charging handle makes loading your weapon much smoother and more manageable, especially for lots of shooting, such as at the range. The charging handle pulls the bolt carrier to the rear to open the breech, eject spent rounds, and then cock the hammer in one fluid motion. Releasing the charging handle strips a round from the magazine and loads it into the chamber.


Popularly called silencers, these components are misunderstood due to popular movies and television. There is virtually no way to silence a high-powered weapon completely. Suppressors muffle the loud muzzle sound from a firearm by trapping the expanding gasses at the muzzle and allowing them to cool slowly. There are designed as a means of hearing protection more than for stealth purposes. 


Rails are the different systems that fasten accessories to AR-15 build kits and numerous other weapons. Optional equipment is attached to the rail and tightened to remain in place for use when aiming, shooting, or otherwise using your gun. 


Handguards attach to the AR-15 barrel to facilitate a better grip for shooting (handling recoil) while shielding the shooter?s hand from heat. 

Bolt Carrier Group 

The bolt carrier group (called the BCG) on your AR-15 is responsible for performing the actual semiautomatic firing mechanism. When you pull the trigger:

  1. The firing pin strikes the primer on the chambered round.
  2. The spend round casing is grabbed and ejected from the chamber.
  3. The hammer is re-cocked for the next round.
  4. A new round is stripped from the magazine and chambered for firing.

Gas Block 

A gas block is a component installed on the barrel of your AR-15 to facilitate semi-automatic fire. The firing procedure described above is fueled by gases released from firing. The block traps excess gas from within the firing chamber and sends it through a small port into a gas tube on top of the barrel and back into the upper receiver. Inside the upper receiver, the gas tube routes the gas back into the system, where its pressure works the firing mechanism. 

Learn More About AR-15 Build Kits 

CBC Industries is a leading AR-15 Build Kits parts and accessories manufacturer. We are based in Charleston, South Carolina, and we proudly employ numerous Unites States military veterans who know about firearms. We?ve been producing quality weapon kits and accessories for years, and our customers support our work with their continued patronage. 

Shop our online store today for AR-15 Build Kits, parts, and accessories for all your rifle and pistol needs.