A Bolt Carrier Group, or BCG, is the heart of the AR-15 platform.
A complete, standard AR-15 BCG is the composition of many individual components; bolt carrier, key, bolt, extractor, firing pin, cam pin, key fasteners & firing pin retaining pin.
Much like the heart of any machine, BCGs require proper care & maintenance.
Luckily, standard AR-15 BCGs are relatively low maintenance; end users can maintain them in the field, by design.
Basic maintenance of a BCG consists of cycles between oiling & cleaning.
Like an engine, to operate reliably, a BCG needs oil.
To protect an oily BCG, standard AR-15s typically utilize a dust cover; a plate which seals the ejection port, where the carrier would otherwise be exposed. When cycled, the carrier pops the dust cover open, which is held by spring tension, to allow ejection of spent cartridges.
While fairly reliable as a platform overall, the standard AR-15’s reliability fades as debris are introduced into the system.
Debris can be any foreign object, most typically a combination of dust, dirt & carbon fouling left from the blowback of fired rounds of ammunition.
Carbon fouling is the result of operating the system, which was originally designed to account for buildup. Some end users actually prefer some buildup as they claim it aids in smoother cycling.
However, as carbon builds up within the system, reliability inevitably suffers until complete failure.
A car can drive without oil, until it doesn’t.
An AR-15 can fire without oil &/or without being cleaned, until it doesn’t.
Therefore, a healthy schedule of cleaning the entire system, but specifically, the BCG, is the only way to ensure optimal operation which establishes reliability & encourages durability.
Most manufacturers describe specific cleaning instructions, but generally, a good rule of thumb is to clean an AR-15 every 500-to-1000 rounds.
Specialized tools can be helpful in cleaning & maintaining a BCG properly. Typically, a solvent or solution, a stiff nylon brush & a soft cloth will clean most BCGs adequately.
Additionally, specialized cleaning kits are an option offered commercially. These kits typically contain all the physical tools & brushes an end user would need to properly maintain an entire AR-15, including the BCG.
Many manufacturers utilize a number of finishes &/or coatings. Diamond-Like Coating, or DLC, for example, aids lubrication & leaves the entire surface much easier to clean. This extends the life-cycle of a particular BCG by reducing the amount of wear during cycling.
Another technique manufacturers use in effort to reduce wear are special “scallop” cuts into the belly, or bottom of the BCG, designed to reduce stress from inserting a fully-loaded magazine. Additionally, some manufacturers also include “sand cuts” or ridged channels, designed to break down debris while cycling, to ensure the action doesn’t lock. The combination of both scallop & sand cuts increase the system’s durability & reliability, especially over standard, mil-spec counterparts.
Once cleaned, the BCG should be oiled again before re-inserting into an upper receiver.
The chart above provided by WeaponEvolution shows us the lubrication points on an AR-15 style BCG. Points marked with “L” should be lightly lubricated with a film barely visible to the eye, while points marked with “G” can be generously applied with your finger.
Understanding how to ensure reliability & increase the durability of the platform through proper maintenance of the BCG is key to utilizing any particular AR-15 effectively.
Did you know that we designed our Grit Cutter BCG to sport special cuts and channels that prevent material from interfering with the carrier and upper receiver even in the presence of dirt, sand, mud, or carbon build-up. Our All-Rounder Carbine C158 BCG comes in both TiN and DLC! Stay tuned because we will have a breakdown of our Grit Cutter BCG coming soon.
