Author Topic: CORRECTING FOR ELEVATION.  (Read 464 times)

0 Members and 1 Guest are viewing this topic.

Offline Sourdough

  • Trade Count: (1)
  • Senior Member
  • *****
  • Posts: 8150
  • Gender: Male
CORRECTING FOR ELEVATION.
« on: September 18, 2009, 07:24:21 AM »
It's easy to get distance from a range finder.  It's also easy to get corrected range for elevation from the right range finders.  but knowing where your bullet is hitting at that range and elevation correction is a bit tricky.

OK some are going to say I don't need that, or I don't shoot long distance and I don't need that.  But think about it a little.  Your sitting in a treestand watching for Whitetail or Hogs.  Off to the side you see through an opening the biggest deer ever.  At 200 yrds, it's farther than you usually shoot, and down hill.  Since it's farther away you want to hold high, but since it's down hill you want to hold low.  What a delima, what do you do?

I faced that delima several times and missed many whitetail back when I was a teen.  Elevation also caused me to miss a few Mulies and a couple of Elk, in New Mexico

There is only one way to find out for sure, go out an shoot up hill or down hill.  Not long distance, just 150, to 300 yards.  300 yards is within the point blank range of most guns and not considered long range by most folks. Once you have mastered that you feel like you have really accomplished something.

Then when the chips are down you miss anyway. 

As you may guess I'm still crying about the wolf I missed with the handi earlier this week.

But elevation really throws a twist into shooting real fast.  Many of our misses are due to elevation and we don't even realize it is there.  I'll be honest here, the Caribou in my avitar was actually missed the first shot.  I shot right over it's back.  I did not realize the elevation difference from where I was and where the Caribou was.  It was walking on the side of a hill, and at first glance you would have thought it higher than I was.  But in actually it was below me.  I shot as though it was level.  That caused my first shot to miss.  I stopped, sat back and realized finally elevation was the differance, second shot I held low, right in the boiler room.
Where is old Joe when we really need him?  Alaska Independence    Calling Illegal Immigrants "Undocumented Aliens" is like calling Drug Dealers "Unlicensed Pharmacists"
What Is A Veteran?
A 'Veteran' -- whether active duty, discharged, retired, or reserve -- is someone who, at one point in his life, wrote a blank check made payable to 'The United States of America,' for an amount of 'up to, and including his life.' That is honor, and there are way too many people in this country today who no longer understand that fact.

Offline PA-Joe

  • Trade Count: (0)
  • A Real Regular
  • ****
  • Posts: 980
Re: CORRECTING FOR ELEVATION.
« Reply #1 on: September 18, 2009, 07:40:54 AM »
In this case, if you hold straight on then you should be good. It's further so you hold high but its on a hill so you hold low. High-low=straight on.

Offline slimak707

  • Trade Count: (0)
  • Member
  • *
  • Posts: 21
Re: CORRECTING FOR ELEVATION.
« Reply #2 on: September 18, 2009, 01:02:19 PM »
well you might as well buy an angle finder and attach it to your scope to fiqure the slope. Or buy a range finder that has slope built in to give the distance for the angle you are shooting. Make a trajectory card, slap it on the side of the stock or in the scope lens cover and adjust THE SCOPE as needed.


www.ustacticalsupply.com/scopedope.aspx

www.longrangesupply.com/index.php?main_page=product_info&products_id=201

Offline tykempster

  • Trade Count: (0)
  • A Real Regular
  • ****
  • Posts: 798
  • I enjoy long range shooting and big guns.
Re: CORRECTING FOR ELEVATION.
« Reply #3 on: September 18, 2009, 03:06:53 PM »
200 yards with anything reasonably flat shooting=disregard anything and hold dead on.

Long distance with angles?  Get a Cosine indicator for your scope so you can multiply the range by the Cosine and figure out what to dial for.

Offline trotterlg

  • GBO Supporter
  • Trade Count: (36)
  • Senior Member
  • *****
  • Posts: 3978
  • Gender: Male
Re: CORRECTING FOR ELEVATION.
« Reply #4 on: September 18, 2009, 04:13:05 PM »
I think most people over compensate for range, I remember my Army rifle instructor telling us that you will never kill anyone by shooting over their head.  Some how it seems wrong, but erroring on the low side is better than shooting high.  Larry
A gun is just like a parachute, if you ever really need one, nothing else will do.

Offline ndindy

  • Trade Count: (0)
  • Member
  • *
  • Posts: 21
Re: CORRECTING FOR ELEVATION.
« Reply #5 on: September 18, 2009, 06:08:29 PM »
The arch of a bullets trajectory is a function of time and travel over only a horizontal plane.  If you think of shooting along a triangle you have



                                                       C



A                                                     B

Shooter A firing at target B has a flat path.  Shooter A to target C has an elevated (or C to A depressed).  The line from A to C is of course longer, but the trajectory is actually A to B (horizontal plane).  If you shoot the distance from A to C, you go high.  If you shoot the same as you would A to B, you have a hit.  Easy :)  Ignore elevation and shoot mentally along level ground.  For rifles it's easy, get your MPBR and hold dead on. 


Offline trotterlg

  • GBO Supporter
  • Trade Count: (36)
  • Senior Member
  • *****
  • Posts: 3978
  • Gender: Male
Re: CORRECTING FOR ELEVATION.
« Reply #6 on: September 18, 2009, 06:32:16 PM »
That's almost true............... the greter the angle the less true it is because the bullet decellerates due to distance traveled not the distance along the horizontal plane.  when shooting straight up the bullet will get to the point of aim at only one point and keep rising, never crossing it again.  Larry
A gun is just like a parachute, if you ever really need one, nothing else will do.