Whether you're building a new AR-15 chambered in 300 blackout or you need a spare bolt carrier group. Here are 5 best 300 Blackout BCG upgrades you can buy. We have over a decade of AR-15 experience to write this guide, and we also want you to know that the 300 blackout BCG is the same as the 5.56 BCG because they share the same shell casing base diameter for the bolt head and extractor to work.
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Understanding 300 Blackout Bolt Carrier Group
The bolt carrier group is a vital component of your 300 Blackout AR-15. It uses the same BCG as the 5.56 AR15. It's primary job is to cycle rounds and reset the trigger system.
It drives the entire gun and is responsible for locking, unlocking, extracting, and ejecting. If the BCG is not well made, it can cause many problems. A well-made BCG increases the predictability of performance.
Recoil and Felt Recoil: A heavier BCG can help reduce both the actual recoil and the felt recoil. This is because the added weight slows down the rearward motion of the BCG during the firing cycle, which in turn reduces the recoil impulse. This can make the firearm more comfortable to shoot, especially during prolonged shooting sessions.
Cycling Rate: The weight of the BCG can also affect the rate at which the firearm cycles rounds. A heavier BCG will generally slow down the cycling rate, which can be beneficial when shooting suppressed.
This is because suppressors increase the backpressure in the firearm, which can speed up the cycling rate. A faster cycling rate can lead to increased wear and tear on the upper receiver components and may also cause reliability issues as round count increases. A heavier BCG for 300 blackout can help counteract this increased cycling rate, potentially improving the reliability and lifespan of the firearm.
Selecting The Best 300 Blackout Carrier Group
When choosing a Bolt Carrier Group (BCG), prioritize those that have passed Magnetic Particle Inspection (MPI) testing, a process that identifies potential defects like cracks or inclusions that could cause future problems.
The BCG's material significantly impacts its durability and weight. While steel is the most common, aluminum and titanium are emerging as lighter alternatives.
Manufacturers often apply finishes to BCGs to boost durability, improve lubricity, reduce maintenance needs, and enhance aesthetics.
BCGs endure substantial wear and tear due to the friction, heat, and spring compression they experience with each round fired from your AR-15. Regular cleaning, maintenance, and quality upgrades can mitigate these effects, preventing most rifle stoppage issues and minimizing BCG wear.
4 Best 300 Blackout Bolt Carrier Groups
PSA 300 Blackout Full Auto BCG
Overall, the Palmetto State Armory 300blk BCG stands out as an excellent premium BCG at a price that's hard to beat. It's compatible with all other mil-spec AR-15 components and has undergone rigorous quality control before shipping out to your door.
It's designed to withstand the brute force of full-auto fire, this BCG is a durable choice for your Semi-Auto AR-15. It's also a budget-friendly option, thanks to the sale and price cuts from PSA, you get what normally would be a $150+ BCG for less than half the price.
Constructed from Mil-spec Carpenter 158 steel, this BCG is designed to handle heavier grain cartridges like subsonic .300 AAC Blackout ammo. Its phosphate outer lining and chrome inner lining ensure heat resistance and durability. Don't be put off by its ashy, flaky appearance upon arrival - this is due to dry packing from the factory. Once you apply lubricant during installation, you'll see the final finish shine through.
Despite its "full auto" tag, this BCG won't convert your semi-automatic rifle into a full-automatic one. It's simply designed to work with full-auto AR-15s and M16s, but it won't affect the function of semi-automatic guns.
2A Armament AR15 Regulated Bolt Carrier Group
If you're willing to invest in one of the best 300 BLK BCG options on the market, the 2A Armament AR15 Regulated Bolt Carrier Group (RBC) is your ideal choice. This BCG is engineered to perfection, with unnecessary material removed to reduce weight and improve performance.
The internals of this BCG are made from variations of 7075-T6, 8620, and 9310 heat-treated steel, ensuring durability. It also features a QPD nitride coating for superior surface wear and corrosion resistance. The standout feature of this BCG is the adjustable titanium gas gate, allowing you to tune the gas system on your AR-15 for optimal performance. This one is best BCG for 300 blackout suppressed shooting.
Toolcraft Left Handed 5.56 Nitride MPI Full-Auto Bolt Carrier Group
Toolcraft is renowned for its quality rifle parts, and this BCG is no exception. Constructed from heat-treated 9310 steel, this BCG is up to 7% stronger than the common 158 carpenter steel used in most BCGs.
This BCG is designed to handle full-auto fire, making it stronger than the usual AR-15 BCG. It's perfect for running your heavier grain .300 AAC Blackout without any issues. If you're a left-handed shooter, this is the ideal bolt carrier group for your AR-15.
FailZero .300 Blackout BCG
The FailZero 300 blackout BCG is praised by many users for its durability, reduced friction, ease of cleanup, and quality of bolts. The BCG is coated with EXO Nickel Boron for butter smoother cycling action. This type of coating is known for its hardness and lubricity, contributing to the BCG's durability and smoothness.
Many AR-15 users appreciates the FailZero bolt, which is made from MIL-SPEC Carpenter 158 steel, and the extractor, which uses a Viton O-ring to enhance tension. The FailZero BCG is also noted for its aesthetic appeal, with some users liking the contrast of the Nickel finish against an all-black rifle. The product is priced at a middle-of-the-road point, making it an appealing choice for those seeking a high-quality 300 blackout BCG
Faxon Firearms Gunner Lightweight .300 Blackout BCG
Faxon Firearms is a well-known name in the firearms market, recognized for its innovative and high-quality products. The Gunner Lightweight Bolt Carrier Group is designed with AR-15s with 5.56mm and .300 Blackout calibers in mind.
This BCG is coated with an eye-catching gold titanium nitride (TiN) finish to increase lubricity, longevity, and prevent corrosion. It also simplifies cleaning and maintenance. High-strength steel components are used in every section of this bolt carrier group to ensure durability. Weighing 8.5oz, it's 25% lighter than most Mil-spec BCGs on the market, making it a great choice if you're looking for a lighter AR build.
Does 300 Blackout Use 5.56 BCG?
Just in case you missed it in the guide, we want to be very clear. Yes, the 300 Blackout AR-15 uses the same bolt carrier group as the 5.56. No extractor change required either. The only change required is the barrel chamber.
Buffer VS Bufferless BCG For 300 Blackout
Bufferless BCG are only useful for a AR-15 platform without a buffer system such as the Sig Sauer MCX or CMMG Dissent 300 Blackout. They are shorter, and they ultimately functions the same as a full size BCG, but they are designed to work with a short stroke or long stroke piston system.
For standard AR-15 builds, please go with the full size BCG.
In general, the buffer weight matters when it comes to reliably cycle the bolt and also fully seat the bolt completely after each shot.
There are 4 popular buffer weight class:
The amount of gas pressure coming back towards the rifle can over gas the system and cause stress damage overtime. When a suppressor is used, the amount of gas pressure can increase. The buffer weight and spring can slow down that bolt.
If a system is overgased, a heavier buffer is required. The easiest way to tell on an AR15 is the ejection pattern of the shell.