The Bolt Carrier Group (BCG) is a critical component in any AR-15 or AR-10 platform. It plays a pivotal role in the firing cycle, as it houses the bolt, which locks into the chamber, fires the round, and then extracts and ejects the spent casing. Without a BCG, these firearms cannot function. However, some firearm enthusiasts prefer customizing their rifles by selecting a “no Bolt Carrier Group” option. This allows them to choose a BCG that best suits their specific needs, such as enhancing accuracy, durability, or ease of maintenance. It’s a testament to the modular nature of these firearms, empowering users to fine-tune their weapons.