!000 yard problem

[charles bonner]

Went out yesterday to shoot three of my rifles at 1000 yards.Target is across a draw and over the tip of a short ridge,Rifles are all zeroed at 100 yards and point of impact confirmed at 400 and 650 yards.Using shooter app on an IPhone ,Berger bullets and G7 BC.
Rifle 1 is a 6.5 x 284 ,Leupold 35 x bench rest scope .Bartline 30" 8 twist ,Berger 140 gr VLD, This rifle shot first 3 shots 1 MOA high and after correction shot a 3 shot 4 " group. I am happy!
Rifle 2 is a 300 WM ,Vortex 6 to 24 FFP Mill dot,Krieger 30" 1 in10 twist ,Berger 210 VLD. IPhone called for 6.9 mill ; to get on target took 8.0 mill.Did a velocity cal. and went back to short range and rifle now shooting way high as expected.Put in the new data for all three yardages - 400- 650-1000- and never could get phone data to agree with firing results.
Rifle 3 was a 6 XC ,Nightforce 12 to 42,30 " Bartlien 30 " 1 in 8 shooting Berger 105 VLD.Results same as the 300WM.
I have reset the 300 and 6 XC back to on target out to 650 but am really at a loss to explain the false information at 1000.Wind is trailing at about 2 mph and shot is almost dead level.Shot direction is SW and coriolis adds only one click to spin drift.Open to ideas .Thanks


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[FearNoWind]

Makes me wonder if your BC data is accurate.

 

[WildRose]

Makes me wonder if your BC data is accurate.

Yep, BC, Velocity, or a combination of both.

 

[charles bonner]

BC numbers are all Litz G7 .Confirmed in his new book and on shooter app. Velocity and BC track correct from 100 through 650 yards confirmed by firing.I do have to change range to extend on out to 1000.It really has me puzzled.I guess I will change locations so I can test all distances to see if there is some type of severe down draft effecting flight at the 1000 yard location.The 6.5 X 284 was fired first and impacted correctly.
There were several other shooters at 1000 and they were all having the same problem.Let you know if I find an answer.Range finder says 1000 yards ; but the only answer that makes sense is a range error -can't explain the 6.5 X 284.

 

[FearNoWind]

Good luck, Charlie. Let us know if you identify another factor.
You didn't describe your 1000 yard range but unless it's perfectly flat from 0 - 1000 there are lots of environmental possibilities.
I found that once I got beyond 600 yards it was a whole new world. Even the most subtle wind shifts, eddies from knolls and other surface irregularities can have an influence on the shot - caliber dependent of course.

 

[Timber338]

What were you guys using to get pressure readings? I shoot long range up in the mountains at all sorts of different elevations, so I am constantly changing my absolute pressure to get my shooting solution.

I did not see that you mention anything about the pressure you were plugging in to you phone, so maybe that's a possible error source ?

 

[Canadian Bushman]

How are you measuring velocity?
What was the wind like that day?

 

[dragman]

Not knowing your equipment or being there the #1 thing I see that would give you those results is scope height.
Any chance you left the standard 1.5 in and didn't adjust it too the 2.25 or the 2.5 that they probably are? that can really throw your data through a loop. gun)

 

[charles bonner]

Range is across a large draw with one low ridge at about 500 yards.Pressure has been set both at weather station and altitude adjusted to Bryon Litz pressure numbers.Wind was a tail wind at about 2 MPH.This is a large flood control pond ( dry). Weather here is so crappy today that I could not shoot but will try to check distance and re shoot tomorrow .Velocity has been checked over a chonograph and confirmed by velocity calibration using Shooter on an IPhone.The data works perfect if the target is 1100 yards -not 1000-I will take a couple of range finders tomorrow and confirm and re shoot.

 

[charles bonner]

Sight height is actual measured center of scope to center of bore on all rifles.

 

[Timber338]

I think you're on track to go back and shoot again. you may not figure out what was going on, but since you said everybody else was having the same problem, then it's not just in your setup.

I've seen wind do some pretty wacky things, so my guess, and totally a guess, would be some abnormal upslope/downslope wind to push the bullet. And with the way mother nature works, she's just trying to **** you off so you'll shoot great tomorrow and your last shooting session will always be a mystery.

 

[charles bonner]

The back side of the small ridge is about a 75 foot vertical bluff.Maybe the tale wind is breaking over that bluff forming a high speed down draft.Tomorrow is another day and if I have the same problem I will go out in the desert and find a flat 1000 yard spot.I have shot out to a mile before so I think my data is on.Just can't figure this one out yet.

 

[yobuck]

Years back before there were books and computers, we would use what data we had
to add elevation then shoot at the chosen target. If we missed we'd make some corrections and shoot again. When we hit the target everybody was happy.
Next time if we'd use the same data chances are we might miss again.
But we knew how to fix that so as to be happy again.
Funny part is a deer would usually wait around till we got it fixed.
Today of coarse were told that we can expect first round hits if we do it right.
But were not told by who, with what, and how often. So it always pays to bring extra ammo and shoot fast so it sounds like an echo rather than a miss.

 

[charles bonner]

I've taken more game at longer ranges with a Win, Mod 70 ( pre 64 ) and a Weaver 4 X and Kentucky windage than I will ever have the chance to take with this high tech equiptment. I love my technology ; and love to shoot paper at long range. Most of my elk now are taken with a ML and I still shoot out to three hundred.I can remember when that was long range!