Problem with calcs for 4dof and strelok

skipglo

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The bc is automatically set when you pick the bullet from the list in the app. I figured since it's hornadys bullet and there app it should be spot on.
What is the BC you put into Strelok...I can check it for you. Also as mentioned above have you shot a box test....those are dramatic differences! Those numbers look like your scope is making about 1.5 MOA per MOA of adjustment.
 

Doozy

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If you suspect scope turrets, tracking etc. Shoot a 100 yard tall target test first. Thatll be good info to have when you call vortex.

Without shooting, you can check your scope with the Horus CATS calibration targets. Their current offering has both MOA and MIL on the target which will tell you if your scope is following one or the other.

 

jdavistx

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@4100 ft, there is no way your pressure is 28.5. More like 25.9.

Good catch. Probably a typo or confusion between barometric and station pressure. I live at 3,005 ft. Weather is clear as I write this. 84˚, 36% RH, SP is 26.93 inHg as measured by my Kestrel with a calculated BP of 30.00 for example.
 

waveslayer

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Has anyone thought of the issue that a Berger bullet and others... that shoot bad at 200 yards will actually stabilize better at longer distances and "settle in" to become more accurate at these longer distances. I have a 30 moa rail and 150 moa of vertical adjustment in my optic and have 105 moa of usable adjustment left once zeroed at 100 yards.... thats a lot of dialing! I don't us it all and a 300 yard zero is what I've changed to.. And also, in 4DOF and Strelok Pro you can verify and correct or validate your shooting as derived in the field with verifed dope added into the program. Another thing, in Strelok Pro make sure you have the "exact" scope picked. I made that error once with my Valdada Recon G2. I picked the wring reticle in mil when there wasn't an option for moa. I sent Igor, the creator of the app, the specs and reticle information for the moa version and he added it. Lastly, I don't know if this would affect thigs but make sure the turret in the scope picked is 1/8 or 1/4 moa clicks. I shoot a 338 LM and Strelok has always been spot on once Verified. I have listened experience with 4DOF. I don't know everything but... I've made those mistakes and tried to have learned from them. Ken.

This has been debated and debunked. Bullets settle way before any distance. It is because at longer distances you are aiming at a finner target, hence the old saying, "Aim small miss small".

Try powering down your scope.

As for the OP. Bad Vortex scope which happens a lot more than people think. Bad inputs as well. 4DOF uses dopler radar to give a custom drag model for each bullet, so some input you are entering is off. Bore to scope height, your SD could be a small factor, zero data, range finder not accurate, etc... you will need to true your scope to the solvers
 

skipglo

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Well I have a odd one for everyone. I have been trying to do some long range shooting using the hornaday 4dof and strelok apps. They have both consistently been way off for my gun. See details below. Any help is appreciated.

4dof says come up 17.93 moa and 0.48 left. Actual hits at 12.35 up and 1.25 left.
Range: 12" steel. 905 yards at 8 degrees down. 0 wind. 68% humidity. 55 degrees. Elevation 4100. Pressure 28.5

Rifle: Savage 10t-sr 300win mag.
26" barrel with 1/10 twist.
178 gr eld-x hornaday 3025fps
Zeroed at 200 yards .3 moa hits constantly

I tried it at 675 yards too. It said to some up 8 moa. Actual hits at 5.25 moa.
1.25 windage with zero wind is also an indication of possible scope error. The .48 is a more reasonable calc when taking in Coriolis effect if shooting North to South ...2-4" max....not 11.31" at 905 yards I'm thinking closer to 2".
 

ndking1126

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Sep 12, 2010
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Given everything you said you had already checked, I also thought moa/mil mismatch on your scope as others have mentioned.

What about the possibility of a different POI based on changing shooting positions after zeroing? I think you said you zeroed prone. Are you shooting at 900 prone also?
 
Last edited:

jdavistx

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Green Valley, AZ
I went through all the inputs and used the kestrel my cousin has. This brought the app down to 17.01. Still no where close.
As for the bullets. I figure since im shooting a 0.3 inch at 200 yards with 178 gr eldx and a 0.5 with the 200gr eldx they should be more than accurate enough for 900. I was unable to get Berger vld under 1 inch at 200 with this rifle.
I'm going to have to use a tall target and see how the scope tracking is.
Either way the gun is consistantly shooting like this. I can come back days later crank it up to 12.25 and smack that steal.

0.3" with a 178gr eldx at 200 yds is the diameter of your bullet (1 hole at 200 yds.) or 0.15 MOA which is, well let's just say exceptional and theoretically 0.15x9 = 1.35" at 900yds. If that is correct, I would look at the inputs going into the software as previously suggested. The gun is not the problem and no quality scope or software is that bad. IMHO.
 

jdavistx

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Mar 13, 2015
Messages
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Green Valley, AZ
I went through all the inputs and used the kestrel my cousin has. This brought the app down to 17.01. Still no where close.
As for the bullets. I figure since im shooting a 0.3 inch at 200 yards with 178 gr eldx and a 0.5 with the 200gr eldx they should be more than accurate enough for 900. I was unable to get Berger vld under 1 inch at 200 with this rifle.
I'm going to have to use a tall target and see how the scope tracking is.
Either way the gun is consistantly shooting like this. I can come back days later crank it up to 12.25 and smack that steal.

Humble suggestion that you research "Station Pressure" vs "Barometric Pressure".

.

The weather channel here says the barometer is 29.65, my kestrel says it is 25.42, 4700 ft above sea level. I do agree, not 5 moa worth though.
Your targets are either not where you think they are, or your input into the app is messed up. Even a half inch miscalculation in sight height really doesn't skew numbers much.
But a combination of bad input may put you that far off.
I just know from shooting, even with your MV and the crappy bullet you are shooting, no way would one normally could hit 900 yards with 12.25 moa up. 17-18 moa seems like it should be closer.
I would look into input in the app.

The Weather Channel and all other reporting provide Barometric Pressure (normalized to sea level), not Station Pressure (pressure at your physical location). Station pressure is what you need. Kestrel reports Station Pressure. Barometric pressure and Station Pressure are only equal at sea level.
 

Eptphil

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Jun 6, 2019
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Location
Sacramento
Well I have a odd one for everyone. I have been trying to do some long range shooting using the hornaday 4dof and strelok apps. They have both consistently been way off for my gun. See details below. Any help is appreciated.

4dof says come up 17.93 moa and 0.48 left. Actual hits at 12.35 up and 1.25 left.
Range: 12" steel. 905 yards at 8 degrees down. 0 wind. 68% humidity. 55 degrees. Elevation 4100. Pressure 28.5

Rifle: Savage 10t-sr 300win mag.
26" barrel with 1/10 twist.
178 gr eld-x hornaday 3025fps
Zeroed at 200 yards .3 moa hits constantly

I tried it at 675 yards too. It said to some up 8 moa. Actual hits at 5.25 moa.
I have had some of the same problems. I had to do the 0 angle calculation vs the 100yd 0, or in your case the 200 yd 0. Also you have to adjust the Axial Form Factor. It may take a few times to perfect it but mine now matches up with to Applied Ballistics App. Also very close to the JBM ballistics app. At first it all matched up until about 600 yds then there was a large difference. So far the correction has been accurate.
 

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