Microbest Military Grade M16 Bolt Carrier Group BCG - Phosphated and Chrome Lined

MSRP: $169.00
Was: $136.00
Now: $129.00
(You save $40.00 )
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bcg-009.jpg Microbest Military Grade M16 Bolt Carrier Group - BCG 

Phosphate finish and chrome lined

Not all bolt carrier groups (BCGs) for the AR15/M4/M16 platform are created equal. Indeed, only a select few manufacturers meet the high standards of military-grade quality. Microbest, with its commitment to exceptional quality materials and stringent testing methods, stands tall among these industry leaders. The Microbest chrome lined phosphate treated BCG has the superior features and attributes of Military Grade M16 Bolt Carrier Group (BCG).

Well, here is the good news.  Charlie's and our sister company, Potomac Armory, went in search of the best military grade BCG, and worked with Microbest to design the specs to the best that can be.  No skimping on steel quality, cheaper hex bolts for the gas key.  All the best materials, and the highest grade quality testing:  High Pressure Testing and Magnetic Particle Inspection (HP-MPI) on a shot-peened Carpenter 158 bolt, and other upgrades.  Many brands that sell rifles to the US military depend upon Microbest, and we believe you can too.

A Focus on Quality and Reliability

Microbest doesn't compromise on material quality for its BCGs. Utilizing top-grade steel and employing high-pressure testing and Magnetic Particle Inspection (HP-MPI) on its shot-peened Carpenter 158 bolts, Microbest ensures durability and reliability in every component it produces. Top-tier brands supplying rifles to the US military often rely on Microbest due to its adherence to superior quality standards.

Understanding the Importance of a Military-Grade BCG

The BCG is a critical component in the AR-15/M16/M4 rifles. It's responsible for loading, firing, extracting, and ejecting the round, essentially serving as the "action" of the weapon. Given the BCG's critical role, it's vital to select a high-quality unit to withstand intensive wear and increased stresses, especially in shorter barrels or with suppressor use. Microbest's military-grade BCGs are designed for robust action, ready for the harsh environments of mud, seawater, sand, and sweat. They can function reliably for extended periods without proper lubrication, an essential feature in demanding combat scenarios.

The Microbest M16 BCG Advantage

The Microbest M16 Full Auto capable bolt carrier group is renowned for its quality and durability. Key features include a manganese phosphate finish for corrosion resistance, a chrome-lined full auto profile 8620 steel alloy carrier, and a shot-peened Carpenter Technology C-158 steel alloy bolt. Microbest's BCGs come with several upgrades over standard milspec BCGs, including shot peening for strength enhancement and precision-ground gas key interface for improved reliability.

Testing a Bolt Carrier Group

Microbest places a strong emphasis on testing to guarantee the superior performance of its BCGs. Microbest's quality assurance is evident in its commitment to rigorous testing, particularly Magnetic Particle Inspection (MPI) and High Pressure Testing (HPT). MPI involves magnetizing the BCG, coating it with magnetic iron particles, and using ultraviolet light to highlight any surface flaws or defects. HPT, on the other hand, tests the BCG's ability to handle the overpressure of sustained live firing.

Microbest ensures that every BCG undergoes individual testing, aligning with the principle that your life may depend on the bolt's resilience. Their bolts, labeled MPI and individually tested for high pressure, utilize C-158 steel - one of the best steel alloys for bolts.

Form Meets Function

Microbest's M16 BCG boasts precision-machined lugs conforming to true mil-spec tolerances. Its outer diameter is machined to all critical surfaces within +/- .0005 inches. The carrier body's outer and inner diameters are hard turned after heat treatment to the same precise measurements. The gas key features rounded leading edges for compatibility with various uppers and buffer tube combinations. Furthermore, the BCG is available with multiple commercial finishes and coatings engineered to its unique tolerances.

Microbest is known visually by its chrome over spray at the front of the carrier.  This extra chrome layer that you see in the front assures that all moving parts of the bolt come in direct contact with hard chrome and not the carrier steel, to assure durability and no wear on the carrier surface.  You have seen this before in other BCGs, like Colt, FN, Daniel Defense, BCM, Sons of Liberty and other brands.  There is no mistake why you see it there.  Microbest is an OEM manufacturer for some of the best military grade bolts and carriers and full bolt carrier groups.  Those names and others.  Maybe some of the others do not demand High Pressure Testing or shot penning, or the most premium of bolts and steel allows.  Some of those names, like Colt and BCM sell for premium prices to have a letter stamped on the side, or a logo engraved, and the reviews for these brands always top the charts of the best available BCGs on the market.

Microbest ensures that every part of its BCG assembly is manufactured to exacting standards. Notably, the carrier is machined from AISI 8620 aircraft quality steel and features a full auto profile with a durable manganese phosphate coating. The bolt, made from Carpenter Technology No. 158 Alloy, undergoes rigorous MPI and HPT to ensure long-term dependability.

All Microbest BCGs come with several upgrades over standard mil-spec BCGs. For instance, the gas key interface on the carrier is precision-ground to enhance its security. The cam pin features a solid film lubricant that reduces wear when the bolt is unlocking. And the firing pin is hard chrome plated to prevent breakage. Such meticulous attention to detail guarantees that your AR-15 will run reliably for many years.

Charlie's brings you the best of the best, and a price that is much lower than it should be

Why?  Because you are not spending money on fancy packaging or brand marketing, or legacy names that command a premium.  And, because Charlie's and Potomac Armory has purchased in volume to bring a great savings to our customers.

While this BCG is rated full-auto, it is not a restricted part, and this BCG will work just as well in an upgraded AR15 rifle, as it will in a military M4 or M16.


  • Manganese phosphate finish for corrosion resistance
  • Full auto profile 8620 steel alloy carrier, chrome lined
  • Hard chromed bore and gas key
  • HPT and MPI Tested
  • Carpenter Technology C-158 steel alloy bolt (shot peened)
  • 4130 Chrome Moly steel alloy gas key with staked Grade 8 hex screws and Loctite sealed
  • 4340 Tool steel extractor (shot peened)
  • S7 Tool steel ejector (shot peened)
  • Mil-spec stainless gas rings
  • 4340 Chrome Moly steel alloy cam pin
  • 8000 series steel alloy firing pin with chrome plating
  • 1038 retaining pin in mag phosphate exterior treatment
  • 15 ounce weight