Odd deer hunting question. [Archive] - Glock Talk

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jdavionic
10-22-2009, 19:32
Hunted many years ago and finally getting back into it. Hunting with a rifle from a tree stand. Let's say you zero your rifle at 25 yds so that it hits zero again at 240 yds (just an example, don't worry about the specific round & trajectory in the example). If you're shooting from an elevated position at a deer 100 yds away, would you expect the elevation / angle are going to have a neglible affect? In other words, if you were shooting level & figured the POI would be almost 3 inches higher than where you aimed for a deer at 100 yds, would it still be about the same if you were shooting from an elevated position in a deer stand (say 20-30 ft up)?

Jonesee
10-22-2009, 21:24
I suppose there is some math that could get to your answer. But why are you asking? Zero your rifle at 100 yards like most everyone else (yes, some zero at 200 yards etc). and hold on the target only allowing less than an inch.

A serious answer would require all the information of the loads you are shooting. a 30.06 trafectory will be substantially different than a 223, than a 30-30. A 30-30 would have the trajectory of a soft pitch softball... Some where on youtube is a guy shooting a 12 ga. shotgun slug 200-300 yards, that has to have the trajectory of a mortar round.


I just saw your sig line with the snipers' creed. With that sig line you should be able to do the math in your head during a gale wind.

jdavionic
10-23-2009, 04:19
I'll give the benefit of the doubt here & assume you didn't quite understand the questions.

I'm going to be hunting from an elevated position with the potential for the deer to be anywhere from 50 yds to 250 yds. Whether you sight your rifle at 100 yds or not is not the point, nor is it what specific adjustment you make for a specific round that you shoot.

The question was just a general question of whether those that have actually hunted in similar environments do anything to account for the elevation affect or not. That's it. The answer that I was looking for is 'yes, I make a slight offset in my aim to account for it' or 'no, it's likely less than an inch difference and doesn't really matter.' I'm not asking for someone to "do the math" for me, which appears to be theme of your reply. I'm asking whether it's worth thinking about or not.

Just curious.

Thanks.

vafish
10-23-2009, 11:58
I'll give the benefit of the doubt here & assume you didn't quite understand the questions.

I'm going to be hunting from an elevated position with the potential for the deer to be anywhere from 50 yds to 250 yds. Whether you sight your rifle at 100 yds or not is not the point, nor is it what specific adjustment you make for a specific round that you shoot.

The question was just a general question of whether those that have actually hunted in similar environments do anything to account for the elevation affect or not. That's it. The answer that I was looking for is 'yes, I make a slight offset in my aim to account for it' or 'no, it's likely less than an inch difference and doesn't really matter.' I'm not asking for someone to "do the math" for me, which appears to be theme of your reply. I'm asking whether it's worth thinking about or not.

Just curious.

Thanks.

Well there is some math involved. The true distance to the deer is the distance from the base of the tree to the deer, but since you are looking at an angle your line of sight is the long side of a 90 degree triangle. Remember high school geometry when you were trying to figure our how tall the flag pole was? Same math equation.

Basically it's going to look further away than it really is, but at 50-100 yards with a high powered rifle and only 20' high the angle really isn't that steep to make a noticeable difference.

Now if you were 30' up in a tree bow hunting 20 yards away, yes it will make a difference. It would also make a difference if you were at the base of a steep mountain shooting up at an angle.

There are some new range finders that have an inclinometer in them that do the math for you.

Tennessee Slim
10-23-2009, 15:09
Too much math. If you're good at guesstimating distance, you can ignore the line-of-sight distance and guesstimate the horizontal distance to the target, then figure your holdover based on that distance. This always will be shorter than the l-o-s distance so your aimpoint always will be a bit lower than the l-o-s distance would indicate.

You can exactly calculate this horizontal distance (cosine of the angle from horizontal times the l-o-s distance) but this still will be a little off because gravity helps the bullet in the downhill shot maintain its velocity but hurts it a bit in the uphill shot. In either case, it'll be less holdover than the horizontal shot. As vafish notes, you could buy a range finder with all that built in (maybe a scope, too, I dunno).

But just how precise do you need to be? A deer's boiler room is pretty big so I don't figure I need all that precision. Besides, that's entirely too much ciphering for me, even when I'm warm and cozy, so I have some crude rules of thumb for when my brain, butt and feet are frozen.

I'm zeroed at 100 yards. Inside that distance, at any angle worth mentioning, I just aim dead-on. I figure the holdunder from the l-o-s angle cancels out the holdover I need because of my scope's height above the bore so I call it a push and aim straight for the sweet spot. The boiler room is so big at that distance, provided my aim is true, a couple of inches one way or the other isn't likely to change the outcome.

For a longer shot, I ignore shallow angles. Okay, subconsciously, I might fudge just a hair, but that's also a reflection of the fast bullet I'm shooting because a faster cartridge is less fussy about the angles. At what my eyeball says is a medium angle, I try to aim low of the sweet spot, about half-way between it and the breast bone. And for a steep angle, dead on the breast bone.

Anyway, that's what works for me.

Sharker
10-25-2009, 05:18
Even when hunting from an elevated stand, the actual distance to the target is measured from horizontal distance. Gravity has no effect "uphill or downhill" to the degree (least from a tree... shooting at high degree angles it will be effected) your referring to. You may lose some horsepower in a high vertical angled shot. The reason you hold under from vertical positions is because pythagorean theorem says the long side of the triangle (hypotenuse) is accounted for by the horizontal distance and the vertical distance. Since gravity effects a bullet at the same rate over any "horizontal" distance, the vertical becomes obsolete. The problem with that is range finders (until recently) are based on line of sight (hypotenuse) where as bullets are effected by the horizontal distance. But for most shooting, just aim at the boiler room and the effect will be so minute that the critter will be down. Bow hunters need to acct for this much more than rifle hunters. Whenever measuring your shot from a tree stand, bow hunters should do so from ground level.

shot1
10-31-2009, 13:05
I would not worry about it because inside 200 yards you are not going to miss a deer if you are shooting for the vitals anyway. If you miss it was you not the angle you are shooting from. If you are shooting most any high power rifle that is pushing a bullet over 2800 fps I would sight in 3 inches high at 100 yards and then you can hold in the center of a deers front shoulder out to 300 yards and not be over 4 inches high or low from muzzle to 300 yards. Aim center and you will kill the deer. I have been doing this for 30 years.