Bushmaster 0020010BLK M4 Built Lower Receiver

The Bushmaster M4 Built Lower Receiver (model 0020010BLK) is a mil-spec forged lower receiver designed as a foundational platform for M4 carbine builds. Machined from 7075 aluminum forgings to XM15-E2S specifications, this component serves as the serialized, regulated firearm portion of an AR-platform rifle assembly. Weighing 2.92 lbs in its completed configuration, it arrives factory-assembled with critical components already integrated, reducing build time for operators and gunsmiths who need a combat-ready starting point.

The receiver ships equipped with a 6-position mil-spec buffer tube, M4 carbine stock, A2 pistol grip, and mil-spec trigger group. These components represent the stock configuration for standard-profile M4 builds and provide a reliable baseline for both patrol and training environments. The 7075 forged aluminum alloy offers the strength-to-weight ratio demanded in tactical carbines, while the mil-spec trigger delivers predictable reset characteristics familiar to military and law enforcement users. The A2 grip angle and stock configuration maintain compatibility with standard M4 ergonomics and accessory ecosystems.

This lower receiver is ideally suited for shooters building or rebuilding M4 carbines for duty use, home defense, or tactical training. Domestically manufactured, the Bushmaster M4 Built Lower Receiver appeals to operators prioritizing mil-spec compliance and proven design over proprietary alternatives. Whether serving as a patrol carbine platform, range trainer, or duty backup, the pre-assembled configuration accelerates deployment while maintaining full customization of upper receiver, barrel, and accessory selection to match mission requirements.