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Advise please

 
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  #15  
Old 08-02-2007, 02:12 PM
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Quote:
Originally Posted by davewilson View Post
Len, i'm sorry but i have to disagree with your answer as to why the bullets impact higher when shooting on an angle. gravity has nothing to do with it. the reason the bullets impact higher is because of the vertical difference of the centerline of the barrel and the line of sight when they're at an
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Originally Posted by davewilson View Post
angle as compared to horizontal.
The reason for a "higher trajectory" is based on the "effective gravity distance"

And as the incline gets stepper the "effective" distance on which the bullet is affected by gravity, becomes shorter, so the drop is less as can be deduced, in short for a given ZR the trajectory will be always "higher" in terms of PATH not in terms of DROP.

That's why at some extent ( moderate ranges and angles ) the "Cosine rule" works. Of course, reality is a little bit more complex than that, and the "rule" is wrong in exact ballistics terms, but as said before, could be a reasonable approach within its operative limits.

Just to illustrate the point, here goes some examples, based on the data as posted. ( I assumed a ZR=100 yards and a SH=1.5 in )






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  #16  
Old 08-02-2007, 08:42 PM
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Gus,i think you're agreeing with me but i must admit all the info you posted is not helping me one way or the other.you say the "path" is higher. that's exactly what i was trying to convey.the angle that's made by the scopes line of sight and the line the barrel makes, works out to a certain vertical distance, at whatever range you're shooting on the level. when you tilt the gun up or down, this vertical distance becomes more. i still don't think gravity has anything to do with it. if you shoot 1k on the level or at any angle, the bullet will have the same hang time. same hang time equals the same amount of drop.
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  #17  
Old 08-03-2007, 09:16 AM
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Quote:
Originally Posted by 300rum View Post
Hi Lefty,

Can you give me the conditions to run them in ballistic program to find your bullet drop:
round grain - 180
bullet BC -
temperature -
elevation (ft) -
muzzle speed (fps) -
distance < 500yards
angle cosine -

As Len mentions, you do not suppouse to have big drop when you are shooting up or down hill not more then 20 degree at that distance, but is better to check just in case....

Thanks Chris

which program u using i dont have one but want to purchase
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  #18  
Old 08-03-2007, 10:47 AM
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Quote:
Originally Posted by Blacktail View Post
which program u using i dont have one but want to purchase
Hi,

My self I used a modified version of Peija Excell Ballistic Software to run on PALM and I'm happy with. (I modified myself to get bullet drop in clicks, and mildot holdovers, plus angle cosine correction, at variable power scope.)
So if I change the power zoom, I just input the new value of the scope in Peija Excell and "I'M ON THE TARGET" again without be worry because I do not have First Focal Plane Reticles.
I choose this options, because I LOVE TO USE MILDOT SCOPE and I could not find a software on the market to have all this options toghether at resonable price.

But there are better software on the market as Exball, from NightForce.

Chris
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  #19  
Old 08-03-2007, 10:59 AM
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Dave,

What I meant to say is that the horizontal component of gravity is what is really affecting DROP since the vertical component is always the same for any angle.

BTW, the perpendicular component is proportionally reduced at the same ratio as the horizontal component.

My apologies if I wasn't clear enough on my previous post, but my intention was to present things as simple as possible.:eek:

The data I posted was just to visualize how the incline angle affects our PATH line.
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  #20  
Old 08-03-2007, 02:00 PM
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Gus, i think the light just went on when i read your last post.makes sense now. i'm sure glad you gave us the simple version!
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