Range, bullet drop, and angle calculator for use with telescopic gun sights

• US 5,960,576 A
• Filed: 09/03/1998
• Issued: 10/05/1999
• Est. Priority Date: 02/04/1998
• Status: Expired due to Term

• Current Assignee: Lou Ann Robinson
• Original Assignee: Bruce N. Robinson
• Inventors: Robinson, Bruce N.
• Primary Examiner(s): Jordan, Charles T.
• Assistant Examiner(s): CHELLIAH, MEENA A
• Application Number:
  US09/146,585
• Time in Patent Office: 397 Days
• Field of Search: 42/90, 42/101, 33/245, 33/298, 33/246
• US Class Current: 42/90
• CPC Class Codes: G06G 1/0057 for gun laying, for bomb aiming

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. An interchangeable alternative rule member is provided to permit the invention to be used to calculate in either metric or English dimensional units.

Claims

1. An apparatus, useable with a telescopic sight having a mildot reticle, for determining the distance to a target of a known dimension, the apparatus comprising:

a first rule member;

a second rule member controllably moveable adjacent to said first rule member;

a mildot scale, comprising mil value marks, on said first rule member;

a range scale, comprising range value marks, on said second rule member;

an index point on said first rule member proximate to said range scale;

a target dimension scale, comprising dimension value marks, on said second rule member; and

said second rule member controllably movable to align a dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, thereby aligning with said index point a range value mark corresponding to the distance to the target.

2. An apparatus according to claim 1, useable with a firearm having a known bullet drop or drift over a known distance, further comprising means for determining an adjustment to firearm elevation or windage to compensate for bullet drop or drift, said means for determining adjustment comprising:

at least one elevation scale, comprising elevation value marks, on said first rule member; and

a bullet drop scale, comprising drop value marks, on said second rule member proximate to said at least one elevation scale;

wherein when said second rule member is controllably moved to align said dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, a drop value mark corresponding to the known bullet drop is concurrently aligned with an elevation value mark, corresponding to the adjustment to firearm elevation or windage, on said at least one elevation scale.

3. An apparatus according to claim 2 wherein said first rule member defines a first rectangular aperture and a second rectangular aperture.

4. An apparatus according to claim 3 wherein said second rule member is controllably movable parallel to said first rule member.

5. An apparatus according to claim 3 wherein said target dimension scale and said range scale are at least partially visible through said first aperture.

6. An apparatus according to claim 5 wherein said bullet drop scale is at least partially visible through said second aperture.

7. An apparatus according to claim 4 wherein said apparatus comprises an obverse face, and said mildot scale, said range scale, said index point, said target dimension scale, said at least one elevation scale, and said bullet drop scale are disposed upon said obverse face.

8. An apparatus according to claim 2 wherein said at least one elevation scale comprises a minute-of-angle elevation adjustment scale and a mil elevation adjustment scale.

9. An apparatus according to claim 2 further comprising means for determining, when there is a vertical angle between said apparatus and the target, the horizontal distance to the target.

10. An apparatus according to claim 9 wherein said means for determining the horizontal distance comprises means for measuring the vertical angle between said apparatus and the target, said means for measuring comprising:

a linear sight on one of said rule members;

a plurality of angle marks on said first rule member; and

a plumb pivotally attached to said first rule member and alignable by gravity with any one of said angle marks;

wherein when said linear sight is aimed at the target, said plumb registers with one of said plurality of angle marks to indicate the vertical angle between the apparatus and the target.

11. An apparatus according to claim 10 further comprising an angle adjustment scale, comprising angle value marks, on said first rule member adjacent to said range scale, wherein an angle value mark corresponding to the vertical angle registers with a range value mark corresponding to the horizontal distance to the target.

12. An apparatus according to claim 2 wherein said range value marks, said dimension value marks, and said drop value marks are labeled in increments of inches or yards on a first side of said second rule member, and further comprising a second range scale, a second target dimension scale, and a second bullet drop scale on a second side of said second rule member, said second range scale having range value marks labeled in metric increments, and said second target dimension scale and said second bullet drop scale having dimension value marks and drop value marks, respectively, labeled in increments of inches or yards, wherein said second rule member is positionable relative to said first rule member to dispose said second range scale proximate to said index point and said second bullet drop scale proximate to said at least one elevation scale.

13. An apparatus according to claim 12, additionally comprising a separate wholly metric second rule member, interchangeable with said second rule member, said wholly metric second rule member having all said value marks labeled in metric increments.

14. An apparatus, useable with a telescopic sight having a mildot reticle, for determining the distance to a target of a known dimension, the apparatus comprising:

a first rule member;

a second rule member controllably moveable adjacent to said first rule member;

a mildot scale, comprising mil value marks, on said first rule member;

a range scale, comprising range value marks, on said first rule member;

an index point on said second rule member proximate to said range scale;

a target dimension scale, comprising dimension value marks, on said second rule member adjacent to said mildot scale; and

said second rule member controllably movable to align a dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, thereby aligning said index point with a range value mark corresponding to the distance to the target.

15. An apparatus according to claim 14, useable with a firearm having a known bullet drop or drift over a known distance, further comprising means for determining an adjustment to firearm elevation or windage to compensate for bullet drop or drift, said means for determining adjustment comprising:

at least one elevation scale, comprising elevation value marks, on said first rule member;

a bullet drop scale, comprising drop value marks, on said second rule member proximate to said at least one elevation scale; and

wherein when said second rule member is controllably moved to align said dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, a drop value mark corresponding to the known bullet drop is automatically concurrently aligned with an elevation value mark corresponding to the adjustment to firearm elevation or windage.

16. An apparatus according to claim 15 wherein said first rule member is generally rectangular and defines a first rectangular aperture and a second rectangular aperture.

17. An apparatus according to claim 16 wherein said second rule member is generally rectangular and controllably movable parallel to said first rule member.

18. An apparatus according to claim 17 wherein said target dimension scale and said range scale are substantially mutually parallel and at least partially visible through said first aperture.

19. An apparatus according to claim 18 wherein said bullet drop scale is generally parallel to said at least one elevation scale and is at least partially visible through said second aperture.

20. An apparatus according to claim 17 wherein said apparatus comprises an obverse face, and said mildot scale, said range scale, said index point, said target dimension scale, said at least one elevation scale, and said bullet drop scale are disposed upon said obverse face.

21. An apparatus according to claim 14 further comprising means for determining, when there is a vertical angle between said apparatus and the target, the horizontal distance to the target.

22. An apparatus according to claim 21 wherein said means for determining the horizontal distance comprises means for measuring the vertical angle between said apparatus and the target, said means for measuring comprising:

a linear sight on one of said rule members;

a plurality of angle marks on said first rule member; and

a plumb pivotally attached to said first rule member and alignable by gravity with any one of said angle marks;

wherein when said linear sight is aimed at the target, said plumb registers with one of said plurality of angle marks to indicate the vertical angle between the apparatus and the target.

23. An apparatus according to claim 22 further comprising an angle adjustment scale, comprising angle value marks, on said first rule member adjacent to said range scale, wherein an angle value mark corresponding to the vertical angle registers with a range value mark corresponding to the horizontal distance to the target.

24. An apparatus, useable with a firearm having a telescopic sight including a mildot reticle and having a known bullet drop or drift over a known distance, for determining the distance to a target of a known dimension and for determining an adjustment to firearm elevation or windage to compensate for bullet drop or drift, said apparatus comprising:

a first rule member;

a second rule member controllably moveable adjacent to said first rule member;

a mildot scale, comprising mil value marks, on said first rule member;

a range scale, comprising range value marks, on said second rule member;

an index point on said first rule member proximate to said range scale;

a target dimension scale, comprising dimension value marks, on said second rule member, said dimension value marks alignable with said mil value marks;

at least one elevation scale, comprising elevation value marks, on said first rule member;

a bullet drop scale, comprising drop value marks, on said second rule member;

said bullet drop value marks alignable with said elevation value marks;

wherein when said second rule member is controllably moved to align a dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, said index point is aligned with a range value mark corresponding to the distance to the target, and a drop value mark corresponding to the known bullet drop simultaneously is aligned with an elevation value mark corresponding to the adjustment to firearm elevation or windage.

25. An apparatus according to claim 24 wherein all said scales and said index point are disposed upon a single planar face of said apparatus.

26. An apparatus according to claim 25 wherein said first rule member defines a first aperture and a second aperture, said second rule member is slidably movable parallel to said first rule member, said mildot scale and said index point are disposed adjacent to said first aperture, said target dimension scale and said range scale are at least partially visible through said first aperture, said at least one elevation scale is disposed adjacent to said second aperture, and said bullet drop scale is visible through said second aperture.

27. An apparatus according to claim 25 further comprising a mildot reticle facsimile on said planar face.

28. An apparatus according to claim 24 further comprising means for determining, when there is a vertical angle between said apparatus and the target, the horizontal distance to the target.

29. An apparatus according to claim 28 wherein said means for determining the horizontal distance comprises means for measuring the vertical angle between said apparatus and the target, said means for measuring comprising:

a linear sight on one of said rule members;

a plurality of angle marks on said first rule member; and

a plumb pivotally attached to said first rule member and alignable by gravity with any one of said angle marks;

wherein when said linear sight is aimed at the target, said plumb registers with one of said plurality of angle marks to indicate the vertical angle between the apparatus and the target.

30. An apparatus according to claim 29 further comprising an angle adjustment scale, comprising angle value marks, disposed on said first rule member adjacent to said range scale, wherein when said second rule member is controllably moved to align a dimension value mark corresponding to the known dimension with a selected mil value mark on said mildot scale, an angle value mark corresponding to the vertical angle registers with a range value mark corresponding to the horizontal distance to the target.

31. An apparatus according to claim 24 wherein said at least one elevation scale comprises a minute-of-angle elevation adjustment scale and a mil elevation adjustment scale.

32. An apparatus according to claim 24 wherein said range value marks, said dimension value marks, and said drop value marks are labeled in increments of inches or yards on a first side of said second rule member, and further comprising a second range scale, a second target dimension scale, and a second bullet drop scale on a second side of said second rule member, said second range scale having range value marks labeled in metric increments, and said second target dimension scale and said second bullet drop scale having dimension value marks and drop value marks, respectively, labeled in increments of inches or yards, wherein said second rule member is positionable relative to said first rule member to dispose said second range scale proximate to said index point and said second bullet drop scale proximate to said at least one elevation scale.

33. An apparatus according to claim 32, additionally comprising a separate wholly metric second rule member, interchangeable with said second rule member, said wholly metric second rule member having all said value marks labeled in metric increments.

34. A method, useable with a firearm having a telescopic sight including a mildot reticle and having a known bullet drop or drift value over a known distance, for determining the range to a target of a known dimension and for determining an adjustment to firearm elevation or windage to compensate for bullet drop or drift, the method comprising the steps of:

a) viewing the target through the scope;

b) observing the number of mildots apparently occupied by the target to determine a mildot value;

c) estimating the actual size of the target to determine a target dimension value;

d) manipulating adjacent mildot and target dimension scales to align respective marks thereon corresponding to the mildot value and the known target dimension value; and

e) viewing the alignment of an index point with a range value mark on a range-to-target scale;

wherein the step of manipulating adjacent mildot and target dimension scales further comprises automatically simultaneously manipulating a bullet drop scale to align a bullet drop value mark with an elevation value mark, on an elevation scale, corresponding to the adjustment to firearm elevation or windage.

35. A method according to claim 34 further comprising determining, when there is a vertical angle between the apparatus and the target, the horizontal distance to the target, wherein the step of determining horizontal distance comprises:

(a) measuring the vertical angle between the apparatus and the target; and

;

(b) viewing the alignment of an angle value mark corresponding to the vertical angle with a range value mark on the range-to-target scale.

36. A method according to claim 35 wherein the step of measuring the vertical angle between the apparatus and the target comprises:

(a) aiming a linear sight at the target;

(b) permitting a plumb connected to the linear sight to pivot by gravity into registration with one of a plurality of angle marks indicating the vertical angle between the apparatus and the target.

37. A method according to claim 36 wherein the step of manipulating adjacent mildot and target dimension scales further comprises simultaneously moving a range value mark corresponding to the horizontal distance into alignment with an angle value mark corresponding to the vertical angle indicated by the one of a plurality of angle marks.