VarmLR Posted May 16, 2020 Report Share Posted May 16, 2020 On 5/13/2020 at 7:57 PM, borbal said: .... or you can simply try it out at http://www.geoffrey-kolbe.com/trajectory.htm where range angle is a variable..... That's a useful reference. Isn't the thread though as much about trying to understand the principles involved and finding perhaps empirical answers to calculating it? Admittedly without something to help with the maths when in the field, if a battery device goes down it's handy just to have a little written table with a list of look up (or down) angles and corresponding horizontal correction for distance as an approximation to the factors involved. Quote Link to comment Share on other sites More sharing options...

gazzarM1 Posted May 16, 2020 Report Share Posted May 16, 2020 Just a thought....if you are shooting either up or down hill and you know (think inclinometer )or can estimate the angle you can apply the cosine of the angle to the actual distance to target.....the lesser distance resulting in your correction to hit the target. As an example distance to target 500 yds....shooting at an angle of 30 degrees (cos .87) ....500 x .87 ....435yds.... apply your correction....a hit. You can carry a card with the formulas already worked out for angles and distances to avoid trying to work out calcs in the field... Quote Link to comment Share on other sites More sharing options...

hiddenmongoose Posted May 17, 2020 Report Share Posted May 17, 2020 On 5/16/2020 at 5:53 PM, gazzarM1 said: Just a thought....if you are shooting either up or down hill and you know (think inclinometer )or can estimate the angle you can apply the cosine of the angle to the actual distance to target.....the lesser distance resulting in your correction to hit the target. As an example distance to target 500 yds....shooting at an angle of 30 degrees (cos .87) ....500 x .87 ....435yds.... apply your correction....a hit. You can carry a card with the formulas already worked out for angles and distances to avoid trying to work out calcs in the field... That is the ''riflemans rule'', which as discussed on page one is not really accurate . COS x dope is simple and much more effective (improved riflemans rule). Try it your self using both methods on steel and see for yourself which is more accurate. I have shot at up to 45 degrees to 600m and 30 degrees to 1000 and depending on size of tgt riflemans rule will actually miss while improved riflemans rule will hit. see @srvet post on page one where he runs the math using the 2 methods and applied ballistics on a 800m 30 degree shot, Improved riflemans rule is within 0.1 of the applied ballistics data whereas the riflemans rule is 1.6 mils of a difference, 1.6mils at 800meters is 128cm of a difference...!." 1.2 meters! As i said go shoot it in real life and you will quickly see that riflemans rule is pretty useless if you really are shooting steep angles and decent distances or small tgts Quote Link to comment Share on other sites More sharing options...

VarmLR Posted May 18, 2020 Report Share Posted May 18, 2020 On 5/16/2020 at 5:53 PM, gazzarM1 said: Just a thought....if you are shooting either up or down hill and you know (think inclinometer )or can estimate the angle you can apply the cosine of the angle to the actual distance to target.....the lesser distance resulting in your correction to hit the target. As an example distance to target 500 yds....shooting at an angle of 30 degrees (cos .87) ....500 x .87 ....435yds.... apply your correction....a hit. You can carry a card with the formulas already worked out for angles and distances to avoid trying to work out calcs in the field... See my post on the previous page...😉 Quote Link to comment Share on other sites More sharing options...

gazzarM1 Posted May 19, 2020 Report Share Posted May 19, 2020 note to oneself to read ALL previous posts ...lol Quote Link to comment Share on other sites More sharing options...

VarmLR Posted May 22, 2020 Report Share Posted May 22, 2020 On 5/19/2020 at 12:44 PM, gazzarM1 said: note to oneself to read ALL previous posts ...lol 😂 Quote Link to comment Share on other sites More sharing options...

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