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Thread: Steep Dall Sheep Shots!

  1. #1

    Default Steep Dall Sheep Shots!

    I've been busy shooting and preparing my rifle for an upcoming dall sheep hunt and have a question in regard to shooting at steep angles? If a ram is 200 or 300 yards down a 45 degree slope would you allow for the same drop as 200 or 300 yards with a flat shot? A rangefinder would likely show the same distance for both but does gravity pull differently on a steep slope? I've heard to hold a little low when shooting down a steep grade but is this correct?

    Question 2, if faced with the same shot but shooting 45 degree angle up a steep hill would you aim a little higher? Hopefully there are some avid sheep hunters/guides out there that can answer this question!

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    Member Vince's Avatar
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    Default

    actually the distance on a 45 deg run is longer then the actual shot.

    the length of the angle is longer then the straight shot would be... so you have to take into account that run....

    draw your self a 45deg triangle.... the up right is labeled A at the bottom. and B at the top....

    the straight horizontal is marked C at the far end...


    A-C is your straight 300 yard shot....

    B-C is your 350 yard angled shot.....

    BUT....

    B-C is REALLY the same as A-C in distance just because you went UP does not mean you got further away.

    there are now range finders to compensate for angle of movment.... but they are $$$ in short..... on any steep angle shot... your gonna aim a tad LOW. if you don't have an accurate reading.....
    "If you are on a continuous search to be offended, you will always find what you are looking for; even when it isn't there."

    meet on face book here

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    Member mainer_in_ak's Avatar
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    Bullets hit higher than point of impact on both uphill and downhill shots. They have an advantage against gravity in both instances. I often use this excuse every time i miss a duck. My buddy still laughs at me and says "let me show you how it's down with my ol browning humpback auto with a cheap 2 3/4" shells"

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    Member Bighorse's Avatar
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    Default trig

    The hypotinus of the triangle (C) is always the longest. The gravitational force exerted on the bullet relates to the shorter, or A and B side of the 90 degree triangle. So whether shooting up or down your still dealing with one of the shorter edges of the triangle effectivly leaving you.........

    SHOOTING A LITTLE LOWER THAN EXPECTED

    Part of this relates to the angle too.....if the angle is steeper than A or B will be shorter.

    With out breaking out a calculatator and taking some fairly intense measurments you can't really exactly calculate whats going on. Hence everyones head scratching and small prayers before letting the lead fly in those situations.

    Good luck on you sheep hunt. I hope this helped.

  5. #5

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    What does Hippopotamus's have to do with Dall Sheep Hunting.....

  6. #6

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    Quote Originally Posted by jimss View Post
    I've been busy shooting and preparing my rifle for an upcoming dall sheep hunt and have a question in regard to shooting at steep angles? If a ram is 200 or 300 yards down a 45 degree slope would you allow for the same drop as 200 or 300 yards with a flat shot? A rangefinder would likely show the same distance for both but does gravity pull differently on a steep slope? I've heard to hold a little low when shooting down a steep grade but is this correct?

    Question 2, if faced with the same shot but shooting 45 degree angle up a steep hill would you aim a little higher? Hopefully there are some avid sheep hunters/guides out there that can answer this question!

    My, RULE is don't over hold or under hold on the first shot. Keep it on the target for the first shot. More animals are overshot on the first shot, than undershot. You are more likely to over estimate the range than under estimate the range. Even more so if shooting across a chasm/gorge/valley, etc.

  7. #7

    Default Rangefinder?

    I guess what you guys are saying is that if I have a rangefinder and it says 300 yards this isn't an accurate distance reading on steep grades? It seems like it would be a straight line from where I am standing to where the sheep is and my rangefinder would have a correct reading? For some reason I was thinking that the gravitational pull on the bullet would be different at steep angles?

    I read something about this in Tony Russ' sheep book and believe he mentioned you don't need to compensate for slope because the distance will be the same?

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    Member Bighorse's Avatar
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    Default Look above

    My friend.....

    The gravitational force on the bullet is variable depending on the angle. The gravitaional force only is relative to the horizontal distance that the bullet travels.

    Hence the jiberish above about trigonometry.

    Those fancy rangefinders can perform the mathematics quickly given the know distance and angle. They then will give you the effective range to work with.

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    Member broncoformudv's Avatar
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    Quote Originally Posted by jimss View Post
    I guess what you guys are saying is that if I have a rangefinder and it says 300 yards this isn't an accurate distance reading on steep grades?
    Yes 300 yards is 300 yards regardless if it is up hill down hill side hill or on flat ground. The issue is gravitational affect on your bullet which changes when you shoot up hill or down hill when compared to on flat ground. When on flat ground you have gravity pulling against the flat surface of your bullet which is the length of it therefore having a greater affect on it than it does when you are shooting up or down hill where gravity is pulling either at an angle or from the base or tip of your bullet where it does not have as much pull so your bullet shoots flatter per say.

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    Talking

    first things first...

    What caliber are you shooting and where is your zero? What bullet? What is your max range?

    Steep grades up hill and downhill will make a difference in point of aim. How much so depends on the above. I have used rangefinders that compensate for up and down hill angles but they are only good to a certain extent. They basically will give you the straight line distance to the target but it won't take into consideration the actual time of flight and trajectory for the actual straight line distance. But the angle compensating rangefinders will work with in reason and with short ranges.

    When you start shooting longer ranges, a lot of long range shooters use an angle cosine indicator on their rifle, or...just measure the angle using a protractor and calculate the change in trajectory.

    For example using a .270 WSM 130gr win silvertip at about 4500 elevation 50 degrees and a 300 yard zero:

    50 degree slope:
    bullet impacts
    100 yards +3"
    200 yards +6.5"
    300 yards +6"
    400 yards +3"
    500 yards -4"

    so with this particular round even at a 50 degree slope you have a margin of 10" out to 500 yards holding dead on. For some that may be acceptable, for some that isn't.

    assuming same cartridge same 300 yard zero. Let's say you range an animal using your angle rangefinder at 200 yards and the actual straight line distances is 400. Your angle of fire is 30 degrees. Based on your rangefinder you would aim for 200 yards which you would expect about 4" high impact from a dead on hold. In reality your bullet is still traveling a total distance of 400 yards and will drop 4" low.

    On a level shot your normal 400 yard shot would drop 8". On a 30 degree slope it would drop only 4" low.
    clear as mud??

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    It is pretty simple, if shooting at angles the bullet strike will always be higher then the bullet strike over flat ground.

    Equation: Straight Line Range
    Slope Angle (factor)

    So they answer that you get from the equation, is the range that you use for the dope on your rifle

    Degree of Slope Factor

    5 .99%
    10 .98
    15 . 96
    20 .94
    25 .91
    30 .87
    35 .82
    40 .77
    45 .70
    Last edited by Knot832; 07-04-2009 at 14:38. Reason: format

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    Quote Originally Posted by Knot832 View Post
    It is pretty simple, if shooting at angles the bullet strike will always be higher then the bullet strike over flat ground.

    Equation: Straight Line Range
    Slope Angle (factor)

    So they answer that you get from the equation, is the range that you use for the dope on your rifle

    Degree of Slope Factor

    5 .99%
    10 .98
    15 . 96
    20 .94
    25 .91
    30 .87
    35 .82
    40 .77
    45 .70
    Knot I think you're using the trigonometry functions for right triangles right?? I think this is also the method that most rangefinders with angle compensation are using as well. This will work to find straight line distance to the target but it doesn't take into account the time of flight that it actually takes to the bullet to fly the total distance to the target....short ranges and depending on the caliber you're shooting I think it will get the job done depending on your kill zone margin.

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    Member BrettAKSCI's Avatar
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    Default

    Quote Originally Posted by Bighorse View Post
    My friend.....
    The gravitaional force only is relative to the horizontal distance that the bullet travels.
    110% correct. Gravitational force only works over the horizontal distance of bullet travel. On a 300 yard shot at a 45 degree angle the horizantal distance from you to the animal can be calculated using the pythagorean theorem. The horizontal distance is 212.13yards. This means you would aim on the animal as if it was 212 yards away on level ground.

    Pythagorean Theorem:

    h squared = a squared + b squared

    h is the hipopatanuse
    a and b are the sides of the triangle and a = b on a 45 degree angle

    300 squared = a squared + a squared

    90,000 = 2a squared

    45,000 = a squared

    square route of 45,000 = a = 212.13 yards

    I hope that clears everything up.

    Brett

  14. #14
    Member AlaskaTrueAdventure's Avatar
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    Lightbulb practice

    jimss,

    Don't you live in Colorado? And Colorado has some hills and a few mountains. If in dought about where to hold on steep angle shots, why not find a really steep slope and practice shooting steep angled shots.

    You arleady know what your gun will do out to 400 hundred yards on level ground. It might be tough finding the perfect 300 or 400 yard steep slope to shoot from, but the practice woule be invaluable.

    Then you could report your results back to us on the forum.

    Dennis
    Alaska True Adventure Guide Service

  15. #15

    Default Calculator!

    Just as I have been dropping ounces from my pack it sounds like I may need to add a calculator...and tape it on my rangefinder! The easiest thing may be to take a couple more hours longer stalk to get within spitting distance so I don't have to worry about a long, angled shot!

    Hey Dennis, Good idea on trying some angled shots in the field! I will definitely have to try it! Not to stink up this post more than I already have, but I imagine elevation and humidity may also change trajectory? How I shoot here in Colo at 9,000' may be different than in AK at 5,000? I have never really worried about sighting in my rifle at 4,500' here at home and hunting sheep and goat at 10,000 to 14,000'...but it may be worth checking out?

    I definitely plan on doing some shooting when I arrive in AK (obviously not in the sheep area).

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    yes, your elevation will affect the air pressure which will affect your trajectory. Temperature will affect it a little bit more. Humidity is basically a non factor. It will affect your shot but to a negligible effect. Definitely try and shoot at a similar elevation that you will be hunting, but ultimately the barometric pressure will be the determining factor. Shots 300 yards and under will probably not be affected very much.

    What I would do instead of taking a calculator. is just making a drop chart with angles.... tape it to your butt stock with clear tape and you're good to go.

    tell you what pm me your email address and I'll make one for you on excel. I'll need some basic info from you though: Caliber, Bullet, Ballistic coefficient if you know it, muzzle velocity, where you're zero'd, max distance you intend to shoot, scope height above bore, approximate elevation you intend to hunt, and approximate temp. If you have actual real world drop values at the ranges you intend to hunt that would be even better. Let me know. I can do it tonight or at work tomorrow.

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    yes it will effect where your bullet hits, and since i am note a math major i went out and purchesed a bushnell scout 1000 with arc. I go threw the menu pick out my bullet puramiters and set it for that. then when i hit the button it will tell me the distance to the target, and how much hold over to have depending apon the angle it reads inside, put the cross hairs where it tells you and send it. The cool thing about the bushnell version is it works for lots of diffrent bullets and also works for archery gear. good luck hope you have the good fortune to be put in that spot, i just hope you can make good on the opertunity.

  18. #18

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    Froggman77, Thanks! I sent you a message and hopefully you got it? May87toy, that is pretty amazing that they have all that in a rangefinder. I have a Bushnell Scout and will have to see if it has the drop calculator....and if it does....try it out! Thanks for the kind note about hitting the spot. This is an opportunity of a lifetime for me so I hope it all pieces together. If not, I ought to have lots of great photos and memories in gorgeous country!

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    hey jmiss, didn't get your pm yet. send over what info you have and I'll work on it tomorrow at work and send you a chart in an excel platform..

    try your rangefinder with the arc. I've only used the nikon which basically uses trig or the "rifleman method" which will get you somewhat in the ball park but like I said, it doesn't take into account the time of flight or actual distance. I don't have any experience with the leupolds or bushnells, if you can enter your MV and other ballistic variables and it will take it into account i think that's some pretty good technology.

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    Just sight in your rifle so you are point blank out to 300 or so and when the time comes to shoot don't overthink it. Put the crosshairs on hair in the kill zone and squeeze the trigger.

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