I just want to make sure my shot's are going were they are supposed to.
I will be going to the East Cape of S.A in March -06 with Madubula Safaris for the smaller antelopes and EC bushbuck and then to Rooiport for Kudu,wildebeest etc.

And I do realize it will depend on velocity ETC..just hoping there is a website to go to.

Thanks Sean

I'm not an expert but I always aim a little bit low when taking shots from a higher angle than the animal.
L

for shooting either uphill or downhill at angles of less than 30 degrees on should forget the angle and shoot as though it was level shooting.

It only gets to be significant when the angle is severe and the distance is long. Forget it and go hunting.

Thanks.


Sean

The idea is that you should hold for the horizontal distance and not the straight line distance. If the angle is A degrees, then the hold should be, ignoring the fact that how the gun might be sighted-in,

Hor. Dist. = Str. line dist (Cos A).

But like vapodog said, just forget it! If you have your calculator handy, you have too much time on your hands!

This is as good of write up as I've seen, scroll to to the bottom for a few different calibre charts (various distance and angles)

http://www.wildsheep.org/magazines/article_uphill_shooting.htm

Will,

Are you sure it is the Cos of A and not the Sin of A?

My trig is a little rusty . . .



Scott

Looks like it is Cos on an uphill shot, and Sin on a downhill shot. Is that correct?



Scott

Pretty sure it's Cos A regardless of whether it is uphill or down.

the correction for 10 degress is

Cos (10) = .984

or, only 2% shorter horizontal distance than the line of sight. At 45 dgress, it is 0.707 so it is 30% less than the line of sight. But like vapodog said, it really isn't significant until the angle gets steep and the critter is way off.

If a 6x6 mulie walks out of the grass at 300 yards at a 30 degree angle (assuming I knew what a 30 degree slope looks like!) I doubt whether I would have the presence of mind to think about it much less make the corrected hold!

quote:

Originally posted by Will:
Pretty sure it's Cos A regardless of whether it is uphill or down.

Well, when shooting downhill, the horizontal distance is the opposite leg, and when shooting uphill, the horizontal distance is the adjacent leg. So it can't be the same, can it?



Scott

Just squeeze the damn trigger!!!!

quote:

Originally posted by TaxPhd:

quote:

Originally posted by Will:
Pretty sure it's Cos A regardless of whether it is uphill or down.

Well, when shooting downhill, the horizontal distance is the opposite leg, and when shooting uphill, the horizontal distance is the adjacent leg. So it can't be the same, can it?



Scott

No, it's the same. Send me a PM with your e-mail adress and I'll send you the figure.

OK, I got it. Uphill, the angle measurement is up from the horizontal. Downhill, it is down from the horizontal. They are the same angles. However, if you draw a picture, and use the actual angle at the top point of the triangle, you will calculate it with sin. If you use the complement of the angle, you use cos.

An accountant trying to understand, much less explain trig., is a scary thing!



Scott

This much I can tell you....if you're shooting straight up or straight down and the distance is about 200 yards.....the bullet will likely hit about 10" high in either case.....if you shoot 400 yards it's enough to miss a silo.

Anything less than this is to be ignored....

a wise old cowboy (O. K. not so wise) always said "aim to hit the damn thing--don't aim to miss!"
just shoot it before it runs!

if you try to do to much hold high or hold low --you are more likely to miss. Most errors are made on distance from target calls--
if you have a range finder and the time to use it, then I would try to make the adjustment on real long shots --shorter distance ---say under few hundred feet, the adjustments are not significant enough to "aim to miss" i.e. hold overs/hold unders.

What I should mention is:
when you shoot up hill or downhill your point of impact will always be higher than expected. The true drop of the bullet is not affected much by the angle -even very steep angles. But, the height of the bullet's path in reference to the shooter's line of sight does change significantly.

The steeper the angle and the farther the distance = more of an effect.

thus, short distances with little angle change from horizonal= not much of an effect so therefore don't worry about and aim to hit -not to miss(no under aiming required)

steep angle (up or down) more under aiming required and as the distance increases, the larger the effect.

unless you have a computer and know all the data(angle of shot, and distance). it will be difficult to be real accurate on steep grades. If you want to do it by pencil, you will also have to have knowledge of your caliber's bullet path, i.e. bullet tables. spend some time figuring using cos - angles.

While you are busy figuring your hold under shot --your buddy can guess at it and shoot your animal! ha-ha

Vapo has the best advice.

I have written a lot on this subject - the hroizontal theory line is a reasonable approximation for moderate angles and distances, but it does not work at long distances. And it only works if you analyze total bullet drop, not path relative to the line of sight.

Gravity only affects a bullet over the horizontal portion of flight? Bullet drop is a function of time of flight, and time of flight is always a function of how much air a bullet has to fly thru. A bullet going 500 yards is going through 500 yards of air, period. Does it hit higher when that 500 yards is an angle? Yea, but not as high as the horizontal theory would lead you to believe. The BC makes a big difference as well.

Put it this way: if the bullet was only affected by the horizontal distance, how come I can't put a bullet into orbit if I shoot it perfectly straight up?

Use a ballastics program like RCBS.Load and see for yourself. Better yet, just go shoot at some angles and see for yourself. Or just listen to Vapo.

Bullets don't travel in a straight line-
you must know where the bullet will be relative to the line of sight through the sights on the gun at the slant angle range distance to the target. You must know bullet path which is; the distance between the line of sight and the position of the bullet at the slant angle distance of the target.

Bullet path is always measured perpendicular to the line of sight. It is positive when the bullet is above the line of sight and negative when the bullet is below the the line of sight.

Drop is the vertical distance between the extended bore line of the gun and the position of the bullet at the slant range distance of the target.
Bullet path and bullet drop is not the same. The shooter needs to know bullet path not bullet drop.
It is true that shooting down(depressed) trajectory is a little flatter(bullet path magnitude is a little less) than the elevated trajectory.
This is caused mainly by a component of the drag force on the bullet keeps the bullet on the downward trajectory from falling quite as fast compared to the bullet on the upward trajectory. On the upward shot trajectory, the component of drag force in the vertical direction is directed downward, causing the bullet to fall a little faster as it flies.

the above info was lifted from http://www.exteriorballistics.com
theres a ten page article on this stuff with comparisions to all of the calculation methods that are popular to figure your holddown amounts. knock yourself out and read it. the graphs are good to view.

If bullets followed the bore line(straight line)--then bullet drop would always be accurate. And yes, at very long distances, there are some other factors that come into play that affect calcs off the "line of sight"---however, they are all related to (and mainly) bullet path influences --less with bullet drop.

Bullet drop is mainly a function of gravity (over distance w/ velocity functions) --that's why gravity is a constant in the calcs (obviously their is some exceptions). At very long distances you do need to take into account loss of velocity, and therefore --that is were bullet drop comes into play---slower moving bullet results in more drop -----less ground covered(by slow speed) causes more drop-----but gravity is constant -LOL

best idea yet --screw all this calc stuff and just get close so you will not have to concern yourself with it. Just shoot the damn thing! ya!

quote:

Originally posted by AnotherAZWriter:
Vapo has the best advice.

I have written a lot on this subject -

how come I can't put a bullet into orbit if I shoot it perfectly straight up?
.

You need a hotter load!!

quote:

Originally posted by quickshot:

The steeper the angle and the farther the distance = more of an effect.

Quickshot: you are absolutely right about this. But every outdoor writer in the world, some of whom live in areas they would have a tough time shooting past 200 and tht are flat as a pancake, expound on this subject by carefully explaining you just hold for the horizontal distance. As you said, you really do need a computer to figure it out.

If you have a flat shooting gun like the 300 W'by family and the distance is 300 yerads or less, just hold in the center and shoot the damned thing. If not, here is the chart which is the same whether you are shooting higher or lower:

flat: 100%
10 degrees: .985
15 : .966
20 : .94
30 : .866
45 : .707

Now if you think you can tell the difference between 30 and 45 degrees in the field, I'll take that bet.

Looking at it another way, 30 degrees at 300 yards comes out to 260 effective yards. You must make a decision if that is important or not to you. It isn't to me.

quote:

Originally posted by Thumpper470:
If you have a flat shooting gun like the 300 W'by family and the distance is 300 yerads or less, just hold in the center and shoot the damned thing. If not, here is the chart which is the same whether you are shooting higher or lower:

flat: 100%
10 degrees: .985
15 : .966
20 : .94
30 : .866
45 : .707

Now if you think you can tell the difference between 30 and 45 degrees in the field, I'll take that bet.

Looking at it another way, 30 degrees at 300 yards comes out to 260 effective yards. You must make a decision if that is important or not to you. It isn't to me.

Thumper: at 260 yards, your drop with a 100 yard zero is 5.8 inches. At 300 the drop is 7.5 inches if the angle is 30 degrees, versus a drop of 9.1 without an angle. The reason I say to ignore it is that the horizontal theory is NOT correct - it would have you hold for 5.8 inches of drop instead of 7.5, which is the correct drop. You are actually better off ignoring the angle in this case. My point is the bullet still has to fly thru 300 yards of air, not 260.

I know we all like to debate how many fairies can dance on a pinhead, but this is a pet peeve of mine.

Anotherazwriter
its apples and oranges
the tables are right.
I agree that 300 yards is 300 yards--thats right! Also, the drop is the same at 300 yards ---regardless if you are shooting on a flat range or on an angle (up or down).

The issue is not how far the bullet is traveling ---nor is it the corresponding drop. The drop is at a constant rate because of gravity as I pointed out earlier.


The issue is this; the angle of the incline induces changes in the "line f sight" which requires a "hold down" amount so that the bullet's path will now cross (line up) with the target.
The bullet drop which is measured from the bore line (also referred to as muzzle line) doesn't correlate the same. You can't exchange the "drop" directly for the "hold down" amount.

Its an apples and oranges kinda thing

what the tables or computers do is this, they take into account the induced changes (of the sightline) from the incline shooting angle to match up the bullets path with he target --not changing the "drop" --I know its read that way --by thats not what the table is doing.

If I get a chance I will expand on this induced change from the sight line and the differance with the boreline calcs stuff later. --no time right now. But will get to it possible tomorrow or next week--it will also answer the question about flat land shooting.
cheers

Quickshot:

Your post here is a bit hard to follow, at least for me.

My point is this: if you use a good ballistics program, the "hold" at an angle does not match the "horizontal theory" hold - you holdover less, but not as much as the horizontal theory would suggest.

Greg Mushdial, who together with his PHD mathematician wife wrote RCBS.Load, also explain the "hold low" theory is due to the sightline changes, not the effect of gravity.

quote:

Originally posted by almostacowboy:
Just squeeze the damn trigger!!!!

Thanks man.....isn't that what I've been saying?????

Get close and you don't have to compensate for anything