Complete Lower Receiver AR15 223/5.56 PlumCrazy Firearms - phoenix sports equipment for sale - backpage.com GunsFX is taking pre-Orders for Plumcrazy Complete Lower Receivers. YES Complete! Shipping will start Mid February. This Fiber Re-Enforced Polymer Composite Lower Receiver is superlite and very strong. Yes stronger than Aluminum it is a Mil-Spec Receiver that will accept any upper assembly. The Lowers have been tested extensively for the past 12 months for durability and reliability. So here is the deal, for $99.95, you will receive a Complete Lower Receiver with free shipping.