Abstract: A recoil device is provided for a gun having a barrel with a breech. The device includes a breech nut, a brake assembly, a pneumatic spring and a counter-recoil buffer. The breech nut has first and second adjacent sides. The brake assembly includes a brake cylinder that mounts to the breech nut on the first side. The pneumatic spring mounts to the breech nut on the second side. The counter-recoil buffer attaches to the pneumatic spring. The brake cylinder and the pneumatic spring internally push fluids for recoil absorption and return in response to firing the gun.

Abstract: A material-actuated door includes a door housing including a flexible material; and one or more least one Shape Memory Alloy (SMA) actuators embedded in the door housing. Each SMA actuator is elastically biased in a first actuator physical state and is configured to transition into a second actuator physical state in response to receiving electrical current. The material-actuated door is transitioned into a first door position in response to disconnecting the electrical current to the at least one SMA actuator, and is transitioned into a second door position in response to delivering the electrical current to the at least one SMA actuator.