Steep Uphill/Downhill with CDS/Kenton/Huskemaw type turret

[bullseyebry]

O.K. Here is a new twist to an old question. While hunting yesterday I attempted a shot at a critter on a STEEP angle. (I did not have my normal L.R. gun) I ranged the animal at 385, the angle was approx. 60 Deg. So............ Being that I can't use MOA because of the type scope. How do I set my scope to the correct yardage? (Keep in mind if it was 50% on the cosine, that is 50% of the MOA or Drop NOT the yardage) ?!?! !!!!

 

[cohunter14]

You can use the cosine on the yardage number, so 50% of 385 is 192.5. I'd dial for approximately 200 yards and you would be good to go.

 

[bullseyebry]

That's kind of the reason I posted. "They" had determined that the percentage had to be applied to the MOA or the Drop and NOT the yardage, because of the disparity. I shot over my intended target 3 times yesterday and hit on the third shot by aiming way low, by using the % times the yardage?!?!?! (BTW, the "THEY" are all the guy's who debated uphill/downhill shots and all the previous post's on the subject)

 

[LazzInc]

that is correct ,,,,, with a 60 degree angle up or down, I believe you multiply the actual range by .5 and then dial the scope for that range ,,,, ((400 actual range X .5, and dial for 200 ,,,,,

if my memory serves me right a 45 degree angle up or down would be about a .7 multiplier ,,,,,

30 degree angle up or down would be an approximate .8 multiplier ,,,,,,

I also heard that there were rangefinders now that did the angle math for you ?

 

[bullseyebry]

I was able to find the article where they go into detail on this:

Link:The Saga Of The Uphill-Downhill Shot, Part I

Check it out!

 

[LazzInc]

about 15 years ago when I was trying to figure this out for myself, ((after shooting right over the top of a trophy Dalls Ram at 350 yards)),,,,,,,

I ran the numbers the old fashion way, with a piece of paper and a ruler ,,,,, this way you can also visually understand the concept better when you can look at it ,,,,,,

all that matters to bullet trajectory is what I call the horizontal distance to the animal or target ,,,,,,

does not matter if you are shooting up or down from horizontal, all that matters is the horizontal distance to the animal ,,,,,

take a large piece of paper or the back of a cardboard box and using a ruler, first draw a perfect 10" X 10" square ,,,,,

then within the square, draw vertical and horizontal graduations every one inch ,,,,,

now assign each inch to equal 100 yards ,,,,,,,,

now draw an imaginary line within that box at whatever angle you want to calculate the horizontal distance for ,,,,,,, and then measure the length of the line, with the ruler, again 1" equals 100 yards ,,,,,,

so if you measure one of your lines at 8" for instance, or 800 Yards, look and see what the vertical line grid it intersects at 8" corresponds to ,,,,,,

if you drew a 45 degree angle line 8" long, it should end up about halfway between the 5th and 6th vertical grid line ,,,,,,,

I hope I am making sense ,,,,,

 

[406precision]

That is a steep shot for sure.... but I am not sure I understand your question are you saying that you were using a non moa scope and had trouble coming up with an effective firing solution???

Most ballistic programs like shooter have the angle compensation built in...also a lot of the new range finders give a true distance to target based on the angle of the shot.

I have a cosign indicator on my elr rifles, but the rangefinder I currently use does the math for me eliminating an error on my part with the math.

If your using a mil type scope or a bdc the most accurate way to get the correct solution would be to use a ballistic program designed for that type of reticle.

 

[sp6x6]

Try a search on this site, been gone over many times. The best is to enter cosine number into your software program,Next I think is called riflemans improved which multiple to your actual moa or mil drop chart. Third is to mutiply cosine to ranged yardage

 

[ramrod79]

Last year I did a lot of steep up, and downhill hill shooting but only to 40 degree angle with my 270WSM with a CDS dial, I used my Leupold TBR 1000 range finder on the TBR mode to range. Range finder compensated for the distance vs angle I dialed shot ,and hit my rock targets.

 

[MontanaRifleman]

O.K. Here is a new twist to an old question. While hunting yesterday I attempted a shot at a critter on a STEEP angle. (I did not have my normal L.R. gun) I ranged the animal at 385, the angle was approx. 60 Deg. So............ Being that I can't use MOA because of the type scope. How do I set my scope to the correct yardage? (Keep in mind if it was 50% on the cosine, that is 50% of the MOA or Drop NOT the yardage) ?!?! !!!!

If your rifle is zero'd @ 300 yds, this shot would be easy. Just put the crosshairs on the animal. Practice on some rocks sometime on a steep hill.

The farther the range, the more complex the solution. For shorter to mid range solutions, firguring the just corrected horizontal distance (like range finders do) is adequate. However, as you get more extreme ranges you must figure in the scope height above bore. Ballistic calculators do this.

Last, if you were purely estimating your slope, you were likely estimating it on the high side. That is the natural tendency. When looking down a 30* slope will look like 45* and a 45* slope will look like 60*.

 

[bullseyebry]

I did not have a P.D.A. With me and was carrying a sporter rifle which I expected to shoot on steep but not extreme angles as well as shorter distances. So basically the question was two part: 1. Determination of correct distance to target and method. 2. Application of that determination to a non-moa dial. This appears to be an issue because if you notice the ad's on LRH , you will see one for a "Gunworks" dial/turret , which has both yardage as well as moa marks. (I posted an article that was on LRH, which would better help understanding my question.) You see the premise of the article was that application of the cosine should be applied to the drop/moa and not to the distance ranged example: 400 yards ranged - 60 Deg. angle - MOA =4.5 Corrected MOA = (4.5x.5) =2.25 So you would dial up 2.25 MOA, which CANNOT be done on a yardage only dial. Using the yardage method it would be 400 X .5= 200 yards which you can do on a yardage dial. My gun is zeroed at 200 so I would not move my dial and just take the shot. I just ran these numbers on a ballistic program and it says I need to dial up 3.3 MOA! All while the target is moving away!

 

[bullseyebry]

Oops!!! I am using an app. on my Iphone. It has a feature that allows you to use the phone to give you the angle by tilting it down the slope, it is inputting an incorrect angle. The corrected MOA for that distance at a 60 deg angle is DEAD ON , no dialing, just shoot!!! LOL Sorry guys! (As far as the angle it was basically straight down. If I let go of my rifle it would have fell 100 ft before it hit a rock. I ranged it 380, my GPS read 6,100 ft. When I got to where the animal dropped it read 5,450 ft. Trust me it was 60 degree's!!!!)

 

[MontanaRifleman]

I did not have a P.D.A. With me and was carrying a sporter rifle which I expected to shoot on steep but not extreme angles as well as shorter distances. So basically the question was two part: 1. Determination of correct distance to target and method. 2. Application of that determination to a non-moa dial. This appears to be an issue because if you notice the ad's on LRH , you will see one for a "Gunworks" dial/turret , which has both yardage as well as moa marks. (I posted an article that was on LRH, which would better help understanding my question.) You see the premise of the article was that application of the cosine should be applied to the drop/moa and not to the distance ranged example: 400 yards ranged - 60 Deg. angle - MOA =4.5 Corrected MOA = (4.5x.5) =2.25 So you would dial up 2.25 MOA, which CANNOT be done on a yardage only dial. Using the yardage method it would be 400 X .5= 200 yards which you can do on a yardage dial. My gun is zeroed at 200 so I would not move my dial and just take the shot. I just ran these numbers on a ballistic program and it says I need to dial up 3.3 MOA! All while the target is moving away!

The most accurate and correct way to do it is with a ballistic calculator that figures in the scope height above bore. You input the slant range and distance along with other enviro data and your scope height is already programmed in the ballistic profile.

But in your case, no PDA and shorter distance shots. The other two ways you ask about are both fine in short to mid ranges depnding on steepness of angle and distance. Dial the MOA or dial the yardage.

In short distances if you know the basic corrections for 30, 45 and 60 degree angles you can approximate distance close enough for a 200 zero. i.e., Your rifle is zeroed @ 200, your actual distance to target is 300 yds on a 45 degree slope. You know instantly you are within your point blank range so slope does not matter. Aim dead on. For a 30* your corrected horizontal range would be 260 which would require additional hold of a couple of inches.

If you zero'd your rifle @ 300, any shot inside 400 yds at any angle is a no brainer dead on hold with a good flat shooting load.

 

[bullseyebry]

Thanks Mark! I learned the hard way yesterday. I want to be as accurate as I possibly can at short distances like 380, so as to be better on the longer one's. i spent some time on the phone with an Army Sniper who gave me some cool data which I promised not to post, but he did say exactly what you said. I gave him the scenario and my hun zero and he said I should have just shot the animal dead on, based on the fact its a .308 dia./180gr. doing 2950. I learned a lot through this situation and now know what to do in the future. Thanks to all!!!