The Angstadt Arms 1045 lower receiver set is the foundation of a quality pistol caliber AR-15. Machined from a solid block of 7075-T6 billet aluminum” the 1045 lower receiver is compatible with 45ACP and 10mm GLOCK magazines. Featuring standard AR-15 controls and accepting most aftermarket Mil-Spec components” the 1045 is instantly familiar to anyone experienced with the AR-15/M4 platform. To aid in reloads” the receiver features a flared magazine well and last round bolt hold open design which locks the bolt open on an empty magazine. The lower receiver can be completed with standard mil-spec components.