Angled shooting question

[Freediver111]

Even though I live out west and have the opportunity to practice shooting at steep angles, I haven’t practiced it yet.

When using a rangefinder like my Leica 1600 R, I range a target and it gives me corrected value after factoring the angle. So for example a 500 yard target at a steep angle, the RF will tell me a corrected LOS distance of say 430. I’m sure you all know this, just being clear.

Now I just plug 430 in my ballistic app, dial, and shoot. I never play with the “look angle” or target angle. I’m assuming entering that value is negated if you use a angle compensating rangefinder which gives you corrected yardage.

Is this a correct assumption? Thanks!

 

[Snuby642]

Tag
I have had limited high angle as well.

 

[domdoc]

Yes

 

[Steel head]

Yes, just shoot using the corrected distance

 

[mudpig]

as stated yes....but.....remember that your wind hold, spin drift etc. will be based on actual distance to target( time of flight).

 

[ShtrRdy]

One possible name for this calculated distance is "Angle Modified Range" . The technique is called "Riflemans Rule". There is some amount of error in using this simplification.

There is another simplification called the "Improved Riflemans Rule" which has you take the cosine of the angle and multiply the Line of Sight ballistic correction. This gets you closer to the correct answer.

The most accurate approach is to plug the angle of the shot into a ballistic computer and have it calculate the most correct answer available.

 

[Lowlight]

No,

Most software will not work right if you use the corrected distance

you want the actual distance and the Cosine in your app, the corrected distance will be off if you use that.


Don't use corrected values from lasers, use actual values and then include the cosine of the angle

 

[308pirate]

No,

Most software will not work right if you use the corrected distance

you want the actual distance and the Cosine in your app, the corrected distance will be off if you use that.


Don't use corrected values from lasers, use actual values and then include the cosine of the angle

Can you explain, in technical terms, why his approach won't work?

 

[Lowlight]

Not now, getting on a plane for AK,

But it's well known not to work, it resolves the information wrong

I thought I might have a video from Bryan Morgan and Hat Creek talking about it with the Kestrel, but again, getting ready to leave

 

[ShtrRdy]

Can you explain, in technical terms, why his approach won't work?

Basically, it's an approximation which has some amount of error. Make up an example and try it on your ballistic program. While your at it try the other two methods I suggested.

If you're not sure how to do that, I might have some time this weekend to put together an example.

 

[308pirate]

Not now, getting on a plane for AK,

But it's well known not to work, it resolves the information wrong

I thought I might have a video from Bryan Morgan and Hat Creek talking about it with the Kestrel, but again, getting ready to leave

No worries. If you have the time later and remember, I'd appreciate some of the gouge.

 

[308pirate]

Basically, it's an approximation which has some amount of error. Make up an example and try it on your ballistic program. While your at it try the other two methods I suggested.

If you're not sure how to do that, I might have some time this weekend to put together an example.

I can run my own scenarios. Like Frank, I'm fixing to travel very soon so don't have the time right now.

 

[Freediver111]

No,

Most software will not work right if you use the corrected distance

you want the actual distance and the Cosine in your app, the corrected distance will be off if you use that.


Don't use corrected values from lasers, use actual values and then include the cosine of the angle

Sounds good! I’ll go back to using the actual distance and cosine. Now to find the manual and figure out how to change that mode in my Leica......Thanks!

 

[domdoc]

If your line of sight range is 500, and your shoot-to range is 430, the angle should be about 30 degrees. If those agree, your equipment got it right. Look at the amount of error that's possible. Say you use the wrong slope number by 10 degrees, and used 20 degrees, which would be a shoot-to of about 470, or roughly 40 yards difference. The scope correction would be off by 2 MOA (about 1 MOA of vertical correction per 25 yards from 300-800 yards, +/-). That would yield an 8-10 inch error in vertical. But if your estimate for cosine was off by a bit, the mistake is not that big. Rule-of-thumb I use is 2, 6, 14, 24, 36, 50, and 66 for 10, 20, 30, 40, 50, 60, and 70 degree angles. The first numbers represent the number of yards to subtract from the LOS range to get the shoot-to range. 500 yard LOS x 14 gives 70 (5 x 14), and the shoot-to is 430 yards. Using cosine you get a shoot-to of 433. The error is negligible. Say the angle was 50 deg - subtract 5 x 36 from 500, and get 320 yards for the shoot-to. Using cosine, you get 321 yards. Again, not enough to sweat. For in-between angles, use the split between the numbers. For a 25 deg angle, use 10 (halfway between 6 and 14). Shoot-to becomes 450 yards. Using cosine, you get 453 yards. At 500 yards, I wouldn't bother about angles up to 20 degrees. The resulting error would land your bullet 5 inches high at most. Just aim for your regular heart shot and the error will give a mid-chest POI. Any error from the rule of thumb numbers will be magnified at longer ranges, but then you're looking at a real-world optimal accuracy of about 2 MOA in hunting situations (maximum 1 MOA from POA to POI), and this number applies to horizontal as well as vertical errors. That's why I would limit myself to a 500 yard shot when a miss (wounded animal) can cost several thousand dollars. If you're shooting at rocks, send it, and correct off your initial impact.