steap up hill down hill shop

[rides bike to work]

What is the proper way to hold over under on a steap up hill down hill shot ?

[hunter1993ap]

i think you take the cosine of the angle and distance.. so if its 500 yards at a 25 degree angle you go 500(cos(25))=453 yards.

[Davey Crockett]

Without getting overly complicated, bullet drop is largely determined by horizontal distance. You really just need to calculate hd given slope and slope distance. With extreme angles and long distances, there are other factors that have to be included (time, gravity, barometric pressure...). There are lots of good calculators out there.
http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

[dino]

What is the proper way to hold over under on a steap up hill down hill shot ?

This is what I bought for my rifle, I practice shooting at some long ranges steep and deep and it works pretty good.

https://www.google.ca/search?q=cosine+angle+indicator&hl=en&rls=com.microsoft:en-us:IE-SearchBox&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=wvBZUOP7J8LtiwKl34DwBg&ved=0CEEQsAQ&biw=1280&bih=823

[Mr. Dean]

The shot will always be higher than *normal*, be it shooting either up or down.
Distance and calibre are the main players.

Typically, if your shooting a high power rifle AND your within its Point Blank Range for distance, a hold on the lower edge of the vitals will ensure a kill shot.

[rides bike to work]

Mr dean you say the shot will be low and I should aim low that doesn't sound right

[Bowzone_Mikey]

horizontal distance ... not line of sight distance is what you aim for

[Mr. Dean]

Mr dean you say the shot will be low and I should aim low that doesn't sound right

My bad SORRY!

The shot will be high because gravity has less surface area of the bullet to work on/with.
Compensate this w/ a lower hold.


Sorry for the F-up, I'll edtit that post.

[Mr. Dean]

The shot will always be higher than *normal*, be it shooting either up or down.
Distance and calibre are the main players.

Typically, if your shooting a high power rifle AND your within its Point Blank Range for distance, a hold on the lower edge of the vitals will ensure a kill shot.




The shot will be high because gravity has less surface area of the bullet to work on/with.
Compensate this w/ a lower hold.




Tied 'em together....

[hunter1993ap]

My bad SORRY!

The shot will be high because gravity has less surface area of the bullet to work on/with.
Compensate this w/ a lower hold.


Sorry for the F-up, I'll edtit that post.


gravity has the same effect on everything on earth. regardless of shooting on an uphill or downhill angle. like others have said you just use the horizontal distance. if you want to test this jump off a cliff and drop a little rock at the same time and you will both hit the water at the same time.

[Mr. Dean]

gravity has the same effect on everything on earth. regardless of shooting on an uphill or downhill angle. like others have said you just use the horizontal distance. if you want to test this jump off a cliff and drop a little rock at the same time and you will both hit the water at the same time.


With the physics and terminology aside, you are correct about which line of the triangle is correct to use for sighting. How to figure that line out in the field, when presented with a target, can be difficult, but with modern firearms and a simple grasp of what is going to happen when fired, it's relitively easy to sort through.

If the deer *looks* 300 yards up/down hill and the gun is PBR sighted in, hold on the lower portion of the boiler room and let-r-rip. :wink:

[hunter1993ap]

With the physics and terminology aside, you are correct about which line of the triangle is correct to use for sighting. How to figure that line out in the field, when presented with a target, can be difficult, but with modern firearms and a simple grasp of what is going to happen when fired, it's relitively easy to sort through.

If the deer *looks* 300 yards up/down hill and the gun is PBR sighted in, hold on the lower portion of the boiler room and let-r-rip. :wink:

souns like what your saying would work well. with my rifle at 300 yards i am 2.5 inches low so i know where i'll be holding at 300 yards. most of the areas i hunt the angle is not enough to make a change in impact so i am lucky but there are a few situations where i might have to think about it a little. one thing that would really work well for angled shots is a rangefinder with the ark setting and a balistic turret to compensate. i have done all the work with my turret but not with angles as it is too much work to bring a calculator and something to measure the angle in the field ;) and i dont have enough money to buy another range finder.

[Walking Buffalo]

True distance, uphill or downhill shot is the horizontal distance between shooter and target.


Basic Trigonometry.

Gravity works across the horizontal plane.

If the target is 500 yards away straight distance from the shooter (C), and the target is 300 yards uphill (B), then the horizontal target disttance (A) is 400 yards. The shooter needs to hold on the target as though it is at 400 yards, not 500 yards.

[Mr. Dean]

souns like what your saying would work well. with my rifle at 300 yards i am 2.5 inches low so i know where i'll be holding at 300 yards. most of the areas i hunt the angle is not enough to make a change in impact so i am lucky but there are a few situations where i might have to think about it a little. one thing that would really work well for angled shots is a rangefinder with the ark setting and a balistic turret to compensate. i have done all the work with my turret but not with angles as it is too much work to bring a calculator and something to measure the angle in the field ;) and i dont have enough money to buy another range finder.

It's a mind-bender that this works both ways (up and down). Many can't grip it.
But what we need to KNOW, is this is what happens and know a way to solve it.

Looky here:
Take a 2x4 stud and with one hand on the end, try to hold it out horizontal - Its tough!
Now start rotating it up.... As the far end gets higher, the easier it becomes untill it passes verticle and starts decending, then it all repeats.

That is EXACTLY what is happening to our bullets as they fly along an angled flight - The flatter it fly's, the harder it is too stay true to the earth.

If we were shooting bottle caps, we would need some serious help but if we're looking at critters that are in our PBR of killing under *normal* circumstances, we just need to remember that they, for shooting sakes, are closer than we think and too allow for some "wiggle room". Knowing your bullets path/trajectory on a level playing field is crucial here.

And if a fella want's to get a grip of the theory, a pellet gun play day is all that's needed.


Hope that helps.

[Hanrahan]

Gravity is a constant force. It always acts 90 degrees to the earth. It is somewhere in and around 9.8 m/s2, or metre's per second squared. If you shoot straight up or straight down there will be no real effect of gravity to bend the bullets trajectory. Parallel to the earth, or a flat shot, produces the most gravitational effect on the bullet. Everything in between is, well, somewhere in between. If you're a math whizz you could figure it out exactly, but I'm not.

In the following diagram, you can see that the true bullet drop is less when shooting up or downhill and will be by the same amount whether up or downhill with the same angle.

This diagram shows three shooting scenarios ; upill, flat and downhill. You'll notice that on the flat shot Do (true bullet drop) intersects Ro (the target) and the bullet trajectory line. This flat shot incorporates the drop factor built into your scope when you sight it in. If you aim where your crosshairs are, you'll hit where you want to - at least theoretically, where these three lines meet.

Now if you look at the uphill or downhill shot, you can see that bullet trajectory does not intersect Ro (target). This is because gravity acts perpendicular to the earth, NOT perpendicular to your bullet path. If you find where Ro intersects your line of sight on the diagram, that is where your crosshairs will be, with no correction. Cock your head sidways and follow the bullet trajectory to get a better idea of what's going on in the uphill or downhill picture. You want the bullet trajectory to cross your line of sight at Ro. In this case it doesn't and the difference between the two is he amount that your bullet will be high.

So, for the SAME line of sight distance, you can see that the bullet will not drop as much in an uphill or downhill shot and if you compensate like you normally would for distance, your bullet may miss high. Result, aim low. I probably didn't describe it well, but the diagram should.


http://www.loadammo.com/Topics/April04.htm

[The Dude]

A rangefinder with built in ARC (Angle Range Compensation) will solve that for you. Shots withing 150 shouldn't matter much, depending on where you sighted in, but long shots, use a rangefinder.

[Jagermeister]

Just hold under in either instance of shooting up-hill or down-hill. Point blank is a reference to the maximum impact area over a given sight-in distance. If you sight your 300 WM in at 220 meters, the point bland would be approximately 290 meters. Essentially, it means that on a horizontal plane, the bullet will strike within an area of 8 to 10 inch diameter. Suffiencient enough to be a killing shot.