Abstract: A vent arrangement is provided to a mask or associated conduit to discharge exhaled gas from the mask to atmosphere. The vent arrangement is structured to diffuse the exhaust vent flow to produce less air jetting, thereby increasing the comfort of the patient and their bed partner. For example, the vent arrangement may include one or more grill components and/or media constructed and arranged to diffuse vent flow.

Abstract: A casing for a relatively soft projectile, such as a projectile for a paintball gun, has a concave portion for receiving a substantially round soft projectile, a driving band located behind the concave portion, and an aerodynamic portion located behind the driving band. The driving band preferably has lands and grooves for engaging rifling in the bore of the gun. The aerodynamic portion may have the approximate shape of a prolate spheroid or a paraboloid of revolution, or another shape that reduces eddy currents and drag behind the projectile. The concave portion of the casing preferably has an adhesive to prevent separation of the casing and projectile in flight. The casing may be solid or hollow; in the later case, it may be filled with a substance such as urethane foam.

Abstract: A method for making a gun barrel for soft projectiles includes providing a mandrel for the bore of the barrel. The mandrel is inserted into a barrel base that can be connected in use to the receiver of a soft-projectile gun. The connected barrel base and mandrel are inserted into a tube. A resin, preferably reinforced, is poured into the space between the inside of the tube and the mandrel. The barrel base, mandrel and tube are surrounded by a pressure chamber. A vacuum is applied to the pressure chamber to de-gas the resin. Then a positive pressure is applied to the pressure chamber to force the tube against the mandrel and resin to form the desired barrel. The mandrel may have rifling impressions. The tube may have a mold shape for forming an ornamental design in the outside of the barrel. Barrels made by the method are also disclosed.

Abstract: In a barrel for a paint-ball gun, the entrance to the bore has a chamfer. The chamfer has a smooth transition from the entrance to the bore; preferably in the form of a section of a circle or parabola. In another embodiment, the bore of the barrel has a similar smooth transition in the muzzle of the barrel at the exit of the bore.

Abstract: A ball sizer for a paint-ball gun includes a bore having an entrance. In the preferred embodiment, the bore has a chamfer, which in turn has a smooth transition from the entrance to the bore of the sizer. The transition may define a section of a parabola, a section of a circle, or a combination of a straight line with a transition to a curve, such as a section of a parabola or circle. Similar transitions may be provided at the exit of the ball sizer, and at the entrance to the barrel attached to the exit of the sizer, or both.

Abstract: In a barrel for a paint-ball gun, the entrance to the bore has a chamfer. The chamfer has a smooth transition from the entrance to the bore; preferably in the form of a section of a circle or parabola. In another embodiment, the bore of the barrel has a similar smooth transition in the muzzle of the barrel at the exit of the bore.

Abstract: A ball sizer for a paint-ball gun includes a bore having an entrance. In the preferred embodiment, the bore has a chamfer, which in turn has a smooth transition from the entrance to the bore of the sizer. The transition may define a section of a parabola, a section of a circle, or a combination of a straight line with a transition to a curve, such as a section of a parabola or circle. Similar transitions may be provided at the exit of the ball sizer, and at the entrance to the barrel attached to the exit of the sizer, or both.