Abstract: A hand-held analog calculator apparatus, and method for use thereof in the field, in association with firearms. The apparatus permits the user of a high-powered rifle equipped with a telescopic sight having a mildot reticle to quickly determine the range to target and the necessary elevation adjustment to compensate for bullet drop. Various logarithmic scales are disposed upon two rule members which slide parallel past each other. The scales display values corresponding to the mildot measurement, estimated target size, known bullet drop, and the like. By manipulating the rule members to align certain selected marks on particular scales, first the range to target value and then the necessary gun sight elevation adjustment and/or sight hold-over values are displayed on other scales. An interchangeable alternative rule member is provided to permit the invention to be used to calculate in either metric or English dimensional units.

Abstract: A hand-held analog calculator apparatus, and method for use thereof in the field, in association with firearms. The apparatus permits the user of a high-powered rifle equipped with a telescopic sight having a mildot reticle to quickly determine the range to target and the necessary elevation adjustment to compensate for bullet drop. Various logarithmic scales are disposed upon two rule members which slide parallel past each other. The scales display values corresponding to the mildot measurement, estimated target size, known bullet drop, and the like. By manipulating the rule members to align certain selected marks on particular scales, first the range to target value and then the necessary gun sight elevation adjustment and/or sight hold-over values are displayed on other scales. Optional components and scales also permit the user to determine any vertical angle between the user and the target, and calculate the horizontal distance to target for purposes of compensating for bullet drop.