US Patent 10415938 Propellant

A propellant in the form of a pellet includes adjoining pellet sections. Each pellet section includes a smokeless powder, a burnable metal, and a polymer. The smokeless powder in each pellet section will in many examples be different from the burn rate of the smokeless powder in other pellet sections. A nonignitable tube passes through the center of the pellet. When the pellet is used within a firearm cartridge, the ignition products from the primer travel through the nonburnable tube, igniting the pellet sections sequentially from the front to the rear of the cartridge. The pressure generated by the propellant within a cartridge casing can be maximized and controlled through the selection of the burn rate for each pellet section.