Abstract: A method for shooting a projectile weapon involves determining the inclination of a line of sight from a vantage point to a target and a line-of-sight range to the target, then predicting a trajectory parameter at the line-of-sight range, for a preselected projectile. Using the trajectory parameter, an equivalent horizontal range may then be determined, wherein the equivalent horizontal range is the range at which the trajectory parameter would be expected to occur if the projectile were shot from the vantage point toward a theoretical target located in a horizontal plane intersecting the vantage point. The equivalent horizontal range may be utilized to compensate for ballistic drop when shooting the projectile weapon. The method may be embodied in a handheld laser rangefinder including a memory for storing ballistic data. Systems for automatic hold over adjustment in a weapon aiming device are also disclosed.

Abstract: A compact spotting scope includes a housing with an outer surface having a grasping region sized and shaped to fit in the palm of a user's hand so that the spotting scope can be held at eye level with one hand in an ergonomic arm and wrist position for steady support. An optical element positioned within the housing is adjusted by manually rotating a side-mounted adjustment knob that extends laterally from the outer surface of the housing opposite the grasping region. The side-mounted position of the adjustment knob allows the arm and wrist of the focusing hand to be maintained in an ergonomic position during manipulation of the adjustment knob, thereby further facilitating steady support. An internal support member of the spotting scope includes a frame portion and a generally tubular portion, which are preferably formed together of unitary one-piece construction for aligning optical elements of the spotting scope.

Abstract: A replaceable battery module for a battery-powered device includes a protective conductive canister sized to receive an electric storage battery. A conductive contact extends through an aperture of the canister for contacting a first terminal of the battery. A second terminal of the battery is electrically contacted by the canister. A preferred configuration of the canister and contact allow both of the terminals of the battery to be accessed from one end of the battery module. A seal is positioned between the canister and the contact for electrically insulating them and for sealing the aperture to prevent leakage of the battery beyond the battery module. A socket for electrically contacting the battery module is formed by a power input terminal assembly mounted within a battery-receiving cavity of a battery-powered device.

Abstract: A portable thermosyphon water heating system for use by outdoor enthusiasts, or others at locations remote from a conventional supply of hot water. Water is heated by an open campfire flame in an enclosed heat exchanger, and is circulated between the heat exchanger and a portable non-pressurized reservoir by thermosyphon action. The hot water returning to the reservoir is discharged through a floating transfer conduit assembly, so the discharge rises and falls with the water level in the reservoir. The floating nature of the hot water return allows the majority of water within the reservoir to be used before refilling is needed, while maintaining thermosyphon action. A method of heating a liquid using the system described above is also provided, along with a retrofit apparatus for retrofitting existing reservoirs to use the thermosyphon principles and components of the present invention.