Rule of Thumb for Shooting Down Hill

[Fishdeeper]

yep, gravity only works over the horizontal distance. But when an animal presents a shot, it can be confusing to start doing cosine calcs in your head.
many rangefinders have a slope function..they give you both the straight line distance to the target, and they give you the slope adjusted distance.
i just use the slope adjusted distance in the Strelok calc, dial the resulting MoA, hold dead on, and never worry about angle.

edit: if you know the angle, say maybe your compass has an inclinometer function, or maybe you've got the Theodolite app on your phone, you can just plug that slope plus the straight line distance into Strelok and it will give you a slope adjusted elevation dial also.

clarification: if you use slope adjusted distance in Strelok, then set slope to 0 degrees. If you use straight line distance, then you must enter the slope angle.

 

[Reelamin]

Try shooting the horizontal distance. I've taught bowhunter education since 94 and the bows back then didn't exactly smoke arrows (we thought they did) . My current set up is only shooting 295 (60 lbs @ 28")

Due to differences in both bow design and anchor point the height of the sight to arrow is a little different for everyone. But horizontal distance works for me. I have a angle compensating range finder and the shoot for range is usually really close to horizontal distance on it.

LOL....funny as my bow is a 94 LX, and I still shoot it because it is still super smooth and will blow threw a deer at 65 yards easily. 64# at 29" with a 410gr arrow. I keep buying guns instead of a new bow because according to the youtube I might gain 10% today, and it still delivers what I need to the yardage I want.

Regardless of bow design, anchor point, etc. is not the sight point (eye or pin) higher than the arrow launch location unless the sight was directly behind the arrow perfectly in line with it? Would the arrow not have to rise to meet that sight line? I'm asking to help understand more as I only have what I have and have seen for other set ups.

 

[Bob Wright]

Yes. Multiple the yardage by the cosine. To get the correct angle you must leave your rifle in its zero. Put the crosshairs on the target and have your spotter use your protractor to get the proper angle. After you get the proper angle then you can convert your angle to cosine. After that, then you can do the math and start dialing for elevation.

This is why I bought a rangefinder that calculates all this in <1 second. It still takes time away from the hunt for practice to verify the rifle and the device you're ranging with. Having a spotter is a luxury to many when hunting. You're either confident or you're not.
I need more practice myself in these exact situations.

 

[greenejc]

Do you live in Colorado? If you do, the best way to find out where to aim and where you will hit is to go and shoot at some targets or rocks with a spotter at distances that you've lazed in and see where that load actually patterns (3 or 4 shots) on the target at 300, 400, 500 and 600 yards, remembering that your distances won't be exactly on the '00' mark for the target, and then recording angle and actual real-world hold over for where you are hunting. Record it in a journal, make a table and then put it on the stock, with 10 degree variations for each distance up to around 30 degrees. Hold center-mass for your target, and don't second guess yourself. Center-mass gives you more error margin at distance, and everyone needs that under real world conditions at ranges beyond 400 yards. B.C.'s, bullet drop calculations, and all the other mathematics used to determine trajectory are approximations and are for the average velocity of your round rather than where your cone of fire will hit. You should shoot at least three shots and see how wide your pattern is. In my case, the 35 patterns three shots into about 5" left and right, which was me, and about 3.5" vertical impact, which is variation in velocity between shots at 610 yards, shooting from sticks while sitting. The use of generated tables will get you in the ball park and help a lot, which shouldn't replace going out and shooting under the conditions in which you will hunt whenever possible. Also, because of the altitude at Green Mountain, which is around 7,500ft, the real world B.C. of the Sierra bullet was actually closer to 0.5 than 0.38, which is the published at-sea-level B.C. of this Gameking as listed by Sierra. That has to be kept in mind, as shots with high B.C. bullets will be noticeably higher at distance in higher altitude.

 

[rse69]

Hi everyone. Got back earlier this week from hunting CO 2nd rifle elk season in GMU 681. Took a cow early on but the bulls were scarce especially given the high winds. At dusk on Weds I had a 5 pt bull appear at 503 yards quartering to and since he was close (30 yds from) a fence (private ranch on the other side), I aimed high on the shoulder (after dialing my Gunwerks 7mm RM shooting 168 gr VLDs to 500 yds) & gently squeezed. My spotter called the shot right over his back. The bull promptly moved off into the timber (not presenting another shot), jumped the fence and minutes later was shot on that private ranch. One more data point, the bull was 10 degrees downhill from me and I had a solid but not perfect rest.

My question is, did I just muff the shot high or should I have dialed a shorter distance on the Viper PST? Do you have a rule of thumb for shooting at high or low angles, like "for 10 degrees, reduce the distance by 10%"?
Thanks for your time & advice!

SWhooting up/down hill is both the same. What the needed piece of information is True Ballistic/Horizontal range (Many rangefinders will provide both). The issue is described in a triangle. The True range is the hypotenuse of the triangle, the true range (in which your bullet is going to experience gravity) is the adjacent leg or the horizontal/ballistic range. If using the true range (hypotenuse leg), your impact will be high. If you dont have a range finder that provides ballistic range then the answer is (True Range * cos(angle(inclination/declination)) ).

 

[greenejc]

This may come across pretty brutal, but before you take a shot at a living breathing thing. You need to understand how to shoot in those type of situation. My advice is get some proper training. As a ethical hunter, we want a quick humane kill. As a hunter, we don't spray and pray. Get some proper training and practice on none living targets.

My guess is he already has plenty of practice and may be just as skilled as most of us. Everyone generates a miss on occasion at distance in real world conditions. Everyone. Anyone who says they haven't just hasn't hunted much. 500 yards is a long shot under real world conditions, firing from sticks or an improvised rest. Firing in the wind from 500 yards down or up hill from sticks or an improvised (tree limb or rock) rest is harder. His only mistake was aiming high third of the elk's chest. ANYONE can make that mistake in the field, and nearly anyone has. Even trained and dedicated snipers have made mistakes like that at distance. Of course, their mistakes are generally made at noticeably greater distances, but I've seen one or two muff a shot at 500. It happens. There are always unforeseen variances that can generate a miss. Always and every time.

 

[dfanonymous]

No sir. It does not matter if you shoot up hill or down hill the math stays the exact same. For instance. If your target is at a LOS of 700 yards, and a 45 degree angle. Up hill the math would be. 700 X ( cosine .707 ) = 494.9 yards. So now do the same 700 yards and the same 45 degree angle and you still get a shoot to range of 494.9 yards down hill shot.

You're going to want to reread what I said before you try to correct me on what "the math is.."

 

[PNWdude67]

I don't know a rule of thumb or formula but angles up or down will result in a high hit,If you know the cosine angle most apps would correct for that

If It truly at was only 10 degrees at 500 the correction is .1 mil which is just shy of 2 inches …you simply missed. When shooting light high recoiling lights rifles it is very important to maintain a good attachment to the rifle and follow through or the shot will fly higher than you intended.

 

[snox801]

Yep as they have stated aim low. I also just got back from CO for mullies.
Shot was 258 yards very steep uphill. I have a zero if 100 yards and didn't have time to check angle. Thanks to the great wisdom on this sight I knew that I just held dead on knowing it would hit high if at 100 and be very close at my range bullet impacted exactly where I was aiming which on a flat plan would be low at that distance.

 

[PNWdude67]

My guess is he already has plenty of practice and may be just as skilled as most of us. Everyone generates a miss on occasion at distance in real world conditions. Everyone. Anyone who says they haven't just hasn't hunted much. 500 yards is a long shot under real world conditions, firing from sticks or an improvised rest. Firing in the wind from 500 yards down or up hill from sticks or an improvised (tree limb or rock) rest is harder. His only mistake was aiming high third of the elk's chest. ANYONE can make that mistake in the field, and nearly anyone has. Even trained and dedicated snipers have made mistakes like that at distance. Of course, their mistakes are generally made at noticeably greater distances, but I've seen one or two muff a shot at 500. It happens. There are always unforeseen variances that can generate a miss. Always and every time.

Yeah, it was not failing yo make a .1 mil correction. The more I train and compete in field matches (not PRS) but hunting style field matches the more I realize and respect the limitations of a given shot scenario.

 

[Blacktailer]

If you are shooting at less than a 15 degree angle, the chnage in horizontal distance is only 5%. It's only at steeper shots that you have to worry about it. At 30 degrees the change is 15% less, at 45 degrees it is 30%.
Like hold overs, know your ballistics and don't over estimate.

 

[greenejc]

Yeah, it was not failing yo make a .1 mil correction. The more I train and compete in field matches (not PRS) but hunting style field matches the more I realize and respect the limitations of a given shot scenario.

From what he was saying, I think he may have been trying for a high chest-spine shot for instant immobilization. That's a good shot, but really hard to pull off at 500 yards with anything in field conditions. Shooting from a less than perfect rest, it becomes harder and if your cone of fire is 4 inches (which is a group size of 0.75 at 100 yards-and a good group from a hunting rifle) an outlier could generate a miss if you were perfect. He just tried for the wrong aim point at the distance. It happens. Wish I could have had a shot like that this year. At least he got a cow and a shot at a nice bull. I spent 8 days and saw only three fresh tracks. I did see about 50 or 60 mulies, and some within 30 feet of me. That was fun.

 

[greenejc]

If you are shooting at less than a 15 degree angle, the chnage in horizontal distance is only 5%. It's only at steeper shots that you have to worry about it. At 30 degrees the change is 15% less, at 45 degrees it is 30%.
Like hold overs, know your ballistics and don't over estimate.

I've practiced shots like this at 30 and 45 degrees in canyons in Colorado just to see where the round impacted at hunting altitude. It makes a considerable difference. At 7600 feet, my 300 win mag will hit over a foot higher than it does at sea level to 1000 feet at 600 yards. Group sizes remain the same, but I have to adjust for zero at 500 to 600 yards for field conditions at that altitude to keep from overshooting past 300 yards. It will be a little low a 100yds, but not enough to generate a miss at a 2" target. It's slightly low at 200, and about dead on at 400 adjusted to hit dead on in my Shepherd at 600 yards. If I expect to shoot that far, I shoot 180 grain Gamekings or Nosler Ballistic Tips at a nominal 3,000fps.

 

[kfreeze]

Years ago I watched when Best of the West (if I remember right) did some uphill and downhill shots to see how much it could cause for error by dialing for the shot that the rangfinder said. They learned that the farther away the shot is, the less the angle will be. In all of their shots they took for the show, none of them ever missed by more than 4" because of the uphill or downhill shot. They said that when it comes to only that variable, it should never be enough to make you miss or have have a really bad shot on a big game animal.