The Angstadt Receiver Set is designed as a quality replacement or an upgrade part for the AR-9/AR45/AR15 build. It's crafted from 7075-T6 aluminum and features a flared mag-well, a threaded bolt catch screw, an integral oversized trigger guard, an ejection port, and a top Picatinny rail for attaching a riflescope or other accessory. These Receiver Sets are available in multiple caliber options, like 9mm, 45 ACP, 5.56mm NATO, or 300 Blackout. The AR15-marked set features M4-style extended feed ramps for optimal feeding and pistol-caliber receivers are compatible with standard AR-15 hammers and accept all aftermarket Glock double-stack magazines.