Abstract: A grounds maintenance system comprising: a robot tractor comprising; a robot body; a drive system including one or more motorized drive wheels to propel the robot body; a control system coupled to the drive system, the control system configurable to store a mow plan that specifies a set of paths to be traversed for a grounds maintenance operation and control the drive system to autonomously traverse the set of paths to implement the mow plan; a battery system comprising one or more batteries housed in the robot body; and a low-profile mowing deck coupled to the robot body, the mowing deck adapted to tilt and lift relative to the robot body, wherein the control system is configured to control tilting and lifting of the mowing deck and cutting by the mowing deck.

Abstract: A grounds maintenance system comprising: a robot tractor comprising; a robot body; a drive system including one or more motorized drive wheels to propel the robot body; a control system coupled to the drive system, the control system configurable to store a mow plan that specifies a set of paths to be traversed for a grounds maintenance operation and control the drive system to autonomously traverse the set of paths to implement the mow plan; a battery system comprising one or more batteries housed in the robot body; and a low-profile mowing deck coupled to the robot body, the mowing deck adapted to tilt and lift relative to the robot body, wherein the control system is configured to control tilting and lifting of the mowing deck and cutting by the mowing deck.

Abstract: A high strength polymer-based cartridge casing includes a cartridge body, molded from a polymer, having a first end and an opposing second end, and enclosing a volume. A bullet is removably engaged with the first end and an insert is engaged to the second end. A shoulder portion is located proximate the first end and a propellant chamber formed in the volume. The propellant chamber has a first diameter proximate to the shoulder, a second diameter proximate to the insert and greater than the first diameter, and a linear slope disposed between the first diameter and the second diameter.

Abstract: A high strength polymer-based cartridge casing includes a cartridge body, molded from a polymer, having a first end and an opposing second end, and enclosing a volume. A bullet is removably engaged with the first end and an insert is engaged to the second end. A shoulder portion is located proximate the first end and a propellant chamber formed in the volume. The propellant chamber has a first diameter proximate to the shoulder, a second diameter proximate to the insert and greater than the first diameter, and a linear slope disposed between the first diameter and the second diameter.

Abstract: A high strength polymer-based cartridge casing includes a cartridge body, molded from a polymer, having a first end and an opposing second end, and enclosing a volume. A bullet is removably engaged with the first end and an insert is engaged to the second end. A shoulder portion is located proximate the first end and a propellant chamber formed in the volume. The propellant chamber has a first diameter proximate to the shoulder, a second diameter proximate to the insert and greater than the first diameter, and a linear slope disposed between the first diameter and the second diameter.

Abstract: A high strength polymer-based cartridge casing includes a cartridge body, molded from a polymer, having a first end and an opposing second end, and enclosing a volume. A bullet is removably engaged with the first end and an insert is engaged to the second end. A shoulder portion is located proximate the first end and a propellant chamber formed in the volume. The propellant chamber has a first diameter proximate to the shoulder, a second diameter proximate to the insert and greater than the first diameter, and a linear slope disposed between the first diameter and the second diameter.

Abstract: A high strength polymer-based cartridge casing includes an upper component of polymer, a bullet of a standard weight, a lower component of polymer, and an insert. The upper component has a shoulder portion and an upper component inner wall has a first diameter extending from the shoulder. The lower component has a lower component inner wall having a second diameter. The upper and lower component inner walls form a propellant chamber; and the first and second diameters reduce a volume of the propellant chamber. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds.

Abstract: A high strength polymer-based cartridge casing includes an upper component of polymer, a bullet of a standard weight, a lower component of polymer, and an insert. The upper component has a shoulder portion and an upper component inner wall has a first diameter extending from the shoulder. The lower component has a lower component inner wall having a second diameter. The upper and lower component inner walls form a propellant chamber; and the first and second diameters reduce a volume of the propellant chamber. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds.

Abstract: A high strength polymer-based cartridge casing includes an upper component of polymer, a bullet of a standard weight, a lower component of polymer, and an insert. The upper component has a shoulder portion and an upper component inner wall has a first slope extending from the shoulder. The lower component has a lower component inner wall having a second slope. The upper and lower component inner walls form a propellant chamber; and the first and second slopes reduce a volume of the propellant chamber. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds.

Abstract: A high strength polymer-based cartridge casing includes an upper component of polymer, a bullet of a standard weight, a lower component of polymer, and an insert. The upper component has a shoulder portion and an upper component inner wall has a first slope extending from the shoulder. The lower component has a lower component inner wall having a second slope. The upper and lower component inner walls form a propellant chamber; and the first and second slopes reduce a volume of the propellant chamber. The reduced volume of the propellant chamber permits only enough propellant to propel a bullet engaged in the cartridge casing at subsonic speeds.