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Discussion Starter · #1 ·


Angled Shooting | Sin City Precision

I wanted to share what I have learned about angled shooting. When the guys and I started out, we would constantly push ourselves to learn more. We covered things like range estimation, moving targets and angles. Before I really started researching I would hear different things, from different people. Some folks said, you would impact differently depending if the shot was up hill or downhill (that is not true). The riflemen’s rule was complicated and took me awhile to decipher it. The math wasn’t something I was going to be able to do quickly out on the range or in the desert.

After some time and practice we figured out how to account for angled shots. We found we preferred using the modified rifleman rule. When you have an angled shot think back to your days in geometry glass. The pythagorean theorem is a way to solve the problem if you have the correct variables. The Pythagorean theorem demonstrates the different between the line of sight range and the actual horizontal range. The line of sight range will be greater than the actual horizontal range. This will cause you to shoot over your target regardless if the shot is up hill or downhill. The severity of the angle will exacerbate the effect.



The easiest way to correct for an angled shot is to measure the angle, use a cheat sheet to find the correct cosine, once you know the cosine take your DOPE for the line of sight range and multiply that by the angle cosine. (A cosine is a way to express an angle in decimal form)

Example:

Line of sight range = 600 yards

Angle = 25 degrees

Cosine = 0.906

DOPE = 11.5 MOA

11.5 (DOPE) x 0.906 (Angle cosine) = 10.419 MOA , dial 10.5 MOA



To find the cosine I use two methods. The first and simplest is a sextant I made using a protractor, straw, string, key ring and tape. Before shooting I will look down the straw and put the target on the center of the straw. The string is weighted and will hang freely, once the target is in the center I will hold still and pinch the string against the protractor. This will tell me how many degrees to my target. Once I know the angle I use a cheat sheet to get the cosine. Now that I have the variables I am able to do the equation to solve for the correct horizontal range.

A faster way to do the same thing is to use an angle cosine indicator. The one I have is made by Sniper Tools Inc. and is mounted to my rifle using a mount from Badger Ordnance. With my scope on zero I put my reticle on the target. While on target I look at the indicator which tells me the cosine for the angle. With that information I can solve for the horizontal range.

With these things figured out, I am able to easily correct for angles. Some of the areas we hunt are located in pretty rough country. Having the ability to accurately solve the problem allows me to send accurate rounds down range.

 

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Discussion Starter · #2 ·
I wanted to point something out or at least attempt to further clarify it. When using the angle cosine to correct for an angled shot you can go about it two different ways. I also wanted to plug a product called the Slope Doper, many MIL/LEO shooters use it to solve for angled shots. They are easy to use and inexpensive.

1. You can use your rifles DOPE instead of correcting for the line of sight range. This is how I did it in the example I gave. 600 yard line of sight range, 25 degree angle (0.906 cosine). My 600 yard DOPE for my 6.5 Creedmoor is 11.5 MOA. 11.5 x 0.906 = 10.419, round up to 10.5 MOA for the shot. I am using the cosine to correct my DOPE for the LOS range.

2. Take the line of sight range and use the angle cosine to solve for the horizontal range. Same parameters, 600 yard line of sight range, 25 degree angle (0.906 cosine). 600 yards x 0.906 = 543.6 yards, now with the range corrected dial your DOPE for 543.6 yards.

In the end both ways of doing it get you to the same point. I just prefer correcting my rifles DOPE because when we were testing out the different ways of doing it, correcting my DOPE was marginally more accurate. The modified riflemen rule is a fast and accurate way to correct for an angled shot, but if you really want to understand what is going on, google “the riflemen rule” and take a look at the math for yourself.
 

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I'm just thinking about getting out and practicing a lot of angle shooting because this past year I came up on a heard of about 20-30 pigs and about 5-700 yards away but the angle was I would say in the 30*'s and didnt want to take a shot as miss or hit and not kill a pig. I'm the type of person that if I'm not sure of my shot its better not to take it. But I have been reading quite a bit about angle shooting now and getting a hang of how its calculated and now have a need for angle indicator. I know my iPhone 4s has something that can work but for heavy duty field work it not easy to use.
 

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Discussion Starter · #4 ·
This is the best tool in my kit for angled shooting.



Simple, easy and cheap. You can pick up a Slope Doper, it does the same thing. Those are also inexpensive. The angle cosine indicator is nice. I only run one on my 6.5 SAUM hunting rifle, on my competition rifle we do not do enough angled shooting to justify having something hang off the gun for it. Some of the areas we hunt here in Nevada are very mountainous so knowing how to dope angles is important.

This fall my team mate Bill harvest a mule deer in North Nevada with a 560 yard LOS range and 29 degree angle. He HEAD SHOT the deer and flicked his "off switch"! The 6.5 SAUM damn near took the bucks head clean off! Great shot and he filled the freezer with meat. We are conservative about the shots we take but shooting practical precision matches has made it so, if we can see it, chances are we can humanly kill and eat it.
 

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You could not have written this post better J!!!! I'm of the same principal. I also have done enough LR shooting now to where I'm pretty much on with my dope notes on my rifle. I have not attempted much angle shooting though. And like you posted my thinking was exact like your writting to use an on the rifle indicator becuase game does not always sit in one place for a long time! So with a indicator right in front of you like that it makes measuring alot easier. Thanks for your post!
 

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Great write-up and information.

For those that want a good "Cosine indicator" and perhaps an anti-cant level at the same time, take a look at the Horus Vision ASLI. Horus Vision

$70 with a variety of mount options. I prefer the rail mount but if you have an extra scope ring that works too as the base of the ASLI has a "dovetail" on it.

I like the combined unit with anti-cant and cosine functions available in the same vision area. Just another option.
 

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Discussion Starter · #9 ·
You could not have written this post better J!!!! I'm of the same principal. I also have done enough LR shooting now to where I'm pretty much on with my dope notes on my rifle. I have not attempted much angle shooting though. And like you posted my thinking was exact like your writting to use an on the rifle indicator becuase game does not always sit in one place for a long time! So with a indicator right in front of you like that it makes measuring alot easier. Thanks for your post!
I'm glad the info is useful and am happy to share it. Next fall cannot come fast enough! Fingers crossed my friends and I get tags for the same zone(s).
 
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