Abstract: A reloadable plastic ammunition casing is provided for firearm use. The plastic casing is preferably constructed from currently available polymeric materials using plastic injection molding techniques. In the preferred embodiment the casing includes a cylindrical body having a top portion and a bottom portion. The top portion having an open end for receiving a propellant and a top lip for retaining a projectile. The bottom portion has an internal casing floor that includes at least one concentric step down towards a centrally located primer pocket such that an installed primer is located in blast communication with the concentric steps on the casing floor. The concentric steps uniformly disburse, distribute, and deflect the heat and gas pressures within the casing when fired, thereby avoiding structural failure, allowing for multiple reloads of a casing constructed entirely out of plastic.