Abstract: The barrel of a firearm is provided with side ports, on opposite sides, adjacent the muzzle. The positioning of the ports, longitudinally of the barrel, is determined according to the pressures of the explosion gases, and the acceleration of the projectile. The acceleration of the projectile occurs in response to, and during, the increase in volume of the explosion gases. This occurs only in a small portion of the length of the barrel, at the breech end, and after that position, the gases decrease in pressure. The recoil occurs after the projectile leaves the barrel and the gases leave the barrel. The side ports are adjacent the muzzle, in the region where the gases have decreased in pressure, and are dimensioned to let nearly all the gases escape by the time the projectile leaves the barrel; they are arranged diametrically opposite each other, and they cancel each other, and greatly reduce and nearly eliminate, the recoil.

Abstract: A storage and viewing device is disclosed for cut film radiographs. The device is provided with a combination of fluorescent lights and a spotlight in a plurality of discrete viewing areas. A transport mechanism moves panel mounted X-rays from a storage area to the viewing area and vice versa. An intermittent drive means is utilized for indexing the display panels into and out of the storage area. Means are provided for controlling the movement of the panels as they are transported to the display area to prevent jamming.

Abstract: Radiation shielding for limiting the transfer of heat by radiation is provided for a ceiling closure having a curtain wall shiftable from an open position allowing air flow through an opening in the ceiling to a closed position in which the curtain wall blocks air flow through the opening. The radiation shielding comprises a plurality of radiation shields formed of air impermeable, heat resistant, flexible fabric sheets folded for storage and for unfolding into generally planar sheets with shifting of the curtain wall into the closed position wherein the fabric sheets define and confine a dead air space. The sheets are preferably made of tightly woven asbestos coated to retain asbestos fibers against liberation into an air stream. Reflective coatings act to retard the radiation of heat.