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ERL Ballistics 'Truing' help

 
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  #1  
Old 06-24-2012, 10:54 PM
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Join Date: Jun 2009
Posts: 83
ERL Ballistics 'Truing' help

I went out today with my .300 Win. Mag. and a bunch of 210 Berger VLD's loaded up to practice a little bit. The rifle shoots very well and I've had great success with this load. The first shot I took was:

1,080 yards
Temp. 76 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +3.4 degrees
Latitude 39.45, azimuth 57 degrees
KAC Bullet flight called for 23.25 MOA and no wind. First shot drilled the milk jug.

Next shot was 1,139 yards on one gallon milk jug
Temp 84 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +4.0 degrees
Latitude 39.45, azimuth 30 degrees
KAC Bullet flight called for 25.25 MOA and 1.75 MOA for 4 mph full value wind wind. First shot was about 0.75 MOA high, 1/4 MOA right. corrected and fired second round and clipped the right side of the jug and rolled it down the hill.

I decided to try one more shot and it was at 1,555 yards on a little bigger than basketball sized rock.
Temp 84 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +5.6 degrees
Latitude 39.45, azimuth 27 degrees
KAC Bullet flight called for 43.25 MOA and 2.5 MOA for 4 mph full value wind wind. First shot was called 3.5 MOA low, good for wind. corrected and fired second round and hit the base of the rock.

I was wondering if anyone had suggestions on how to true my ballistics calculator a bit better. It is spot on out to about 1,100 yards and then I start having errors. I have chronographed my load extensively and I'm confident in my MV and ES is in the 12-15 fps range. I'm getting atmospherics from a Kestrel 4500, measuring range with both a Bushnell 1500 and Leupold RX-IV rangefinder. I have a Leupold VX-III and have checked the tracking on it and have inputted the correction factor into the program. I am also running a single G7 BC of 0.323. If anybody has any ideas on what to try to help bring the output of this program more in line with the results I'm getting? Thanks in advance for any advice.
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  #2  
Old 07-02-2012, 12:40 AM
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Join Date: Feb 2005
Location: Nevada
Posts: 2,781
Re: ERL Ballistics 'Truing' help

What's your average Muzzle Velocity?

What distance did you zero in for?

What is your scope height?

Do you have info for your zero condition?

When you zeroed it in, was the angle slope 0?
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HEBREWS 13:8
Jesus Christ the same yesterday, and to day, and for ever.

Our Lord Jesus said that as it was in the days of Noah and
also as it was in the days of Lot so it shall be in the days...
It's happening again!!! God sent to us His prophet, and His Word
to this generation and we once more are rejecting it as was prophesied!!!

---> As promised, God Sent His Prophet to us!
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  #3  
Old 07-02-2012, 08:38 AM
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Location: Blackfoot, Idaho
Posts: 8,060
Re: ERL Ballistics 'Truing' help

Eaglet is asking the right questions!
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  #4  
Old 07-03-2012, 12:27 AM
Bronze Member
 
Join Date: Jun 2009
Posts: 83
Re: ERL Ballistics 'Truing' help

Quote:
Originally Posted by Eaglet View Post
What's your average Muzzle Velocity?

What distance did you zero in for?

What is your scope height?

Do you have info for your zero condition?

When you zeroed it in, was the angle slope 0?
MV- 2940 measured by Chronograph at 15'. Was 38 degrees F outside when chronographed, load is with H1000. 2970 fps input into program which trued program to 1000 on paper well.

Zero range - 202 yards

Scope height - 2.045" center of bore to center of objective

Zero input conditions - Yes, all zero conditions taken from Kestral and inputted directly into program. Angle of slope was measured at 2 degrees uphill.

Did I get them all?
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  #5  
Old 07-03-2012, 03:10 AM
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Join Date: Feb 2005
Location: Nevada
Posts: 2,781
Re: ERL Ballistics 'Truing' help

I'm trying to get info from you to see if I can get the same numbers you're getting.
When you zeroed the gun, it seems to me it was done on a different day.
If that's so, I would like to get those values... to input them as zero conditions and
use the other ones you have already given us as "field condition".

Did you re-zero on this day?
Quote:
I went out today with my .300 Win. Mag. and a bunch of 210 Berger VLD's loaded up to practice a little bit. The rifle shoots very well and I've had great success with this load. The first shot I took was:

1,080 yards
Temp. 76 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +3.4 degrees
Latitude 39.45, azimuth 57 degrees
KAC Bullet flight called for 23.25 MOA and no wind. First shot drilled the milk jug.
Thanks...
__________________
-----------------------------

-----------------------------
HEBREWS 13:8
Jesus Christ the same yesterday, and to day, and for ever.

Our Lord Jesus said that as it was in the days of Noah and
also as it was in the days of Lot so it shall be in the days...
It's happening again!!! God sent to us His prophet, and His Word
to this generation and we once more are rejecting it as was prophesied!!!

---> As promised, God Sent His Prophet to us!
Reply With Quote
  #6  
Old 07-03-2012, 07:00 PM
Bronze Member
 
Join Date: Jun 2009
Posts: 83
Re: ERL Ballistics 'Truing' help

Eaglet, I appreciate your help with my frustrations. Below is the 'Zeroing conditions' copied directly from my ballistics program. I did not rezero on the day I fired the shots mentioned above. I've never had my zero wander on my scope, but maybe I should have checked that though.

MV - 2970fps
Zero Range - 202 yards (Not high or low of aim point thus no Y-intercept was needed)
Sight Height - 2.045"
Temp - 87 degrees F
Station Pressure - 24.50 inHg
Angle - 2 degrees uphill
RH - 30 percent
Altitude - 0 ft (This is required of my program when station pressure is used)
G7 BC - 0.323 lb/in^2
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  #7  
Old 07-04-2012, 05:40 AM
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Join Date: Feb 2005
Location: Nevada
Posts: 2,781
Re: ERL Ballistics 'Truing' help

Quote:
Originally Posted by BigBboy25 View Post
I went out today with my .300 Win. Mag. and a bunch of 210 Berger VLD's loaded up to practice a little bit. The rifle shoots very well and I've had great success with this load. The first shot I took was:

1,080 yards
Temp. 76 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +3.4 degrees
Latitude 39.45, azimuth 57 degrees
KAC Bullet flight called for 23.25 MOA and no wind. First shot drilled the milk jug.
My solution, using spin drift and Coriolis, says: 23.6 MOA---That would still put
you within 2.83" higher from your shot, still on the milk jug! (1 clic difference)


Next shot was 1,139 yards on one gallon milk jug
Temp 84 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +4.0 degrees
Latitude 39.45, azimuth 30 degrees
KAC Bullet flight called for 25.25 MOA and 1.75 MOA for 4 mph full value wind wind. First shot was about 0.75 MOA high, 1/4 MOA right. corrected and fired second round and clipped the right side of the jug and rolled it down the hill.
My solution: 25.7 MOA (2 clics = 0.5 MOA higher than your POI) and 2.1 MOA for wind compensation.

I decided to try one more shot and it was at 1,555 yards on a little bigger than basketball sized rock.
Temp 84 F
Barometric Pressure 24.48 in Hg
Humidity 13 percent
Angle +5.6 degrees
Latitude 39.45, azimuth 27 degrees
KAC Bullet flight called for 43.25 MOA and 2.5 MOA for 4 mph full value wind wind. First shot was called 3.5 MOA low, good for wind. corrected and fired second round and hit the base of the rock.
My solution: Vertical 44.4 MOA; 4.3 for wind. This here would have placed you 1.25
MOA closer to POI.

I was wondering if anyone had suggestions on how to true my ballistics calculator a bit better. It is spot on out to about 1,100 yards and then I start having errors. I have chronographed my load extensively and I'm confident in my MV and ES is in the 12-15 fps range. I'm getting atmospherics from a Kestrel 4500, measuring range with both a Bushnell 1500 and Leupold RX-IV rangefinder. I have a Leupold VX-III and have checked the tracking on it and have inputted the correction factor into the program. I am also running a single G7 BC of 0.323. If anybody has any ideas on what to try to help bring the output of this program more in line with the results I'm getting? Thanks in advance for any advice.
My advice is like this:
If you're zeroed at 202 yd, place vertical targets at 500 yd, 800 yd and 1200 yd. Shoot at least 3 shot group to each after adjusting for vertical elevation
according to your program. Measure from the center of the group so see what
adjustment you'll need for each. Of course the 202 will not need adjustment.
Then, since you're pretty sure about your muzzle velocity, then make small adjustments
to the BC until it matches the values that it should have.
For example, let's say the program says for 1000 yd you need to go
up 23 MOA but the 3 carefully taken shots measure 9" high so...
9/1.047/10 = 0.8 MOA from center of the 3 carefully taken shots. Then you make
small adjustments until your app says 22.2 MOA up. Hopefully those small adjustments will allow you to get to a point very close to all distances being pretty
close.

Some folks are fully sold on Litz's G7 BC and they make adjustments on the muzzle velocity until you get as close of a match as possible. Others, adjust the BC
ad others adjust both which I don't think is such a good idea.

In any event you have a pretty good idea of how to go about it.

NOTE: I'm taking for granted that the rifle and the shooter are capable to hold small groups at all distances. :-)
__________________
-----------------------------

-----------------------------
HEBREWS 13:8
Jesus Christ the same yesterday, and to day, and for ever.

Our Lord Jesus said that as it was in the days of Noah and
also as it was in the days of Lot so it shall be in the days...
It's happening again!!! God sent to us His prophet, and His Word
to this generation and we once more are rejecting it as was prophesied!!!

---> As promised, God Sent His Prophet to us!
Reply With Quote
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