Problem with calcs for 4dof and strelok

jdavistx

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Here's a fun question. The literature I looked at for a Vortex Viper HS-T 6-24x50 says it's 2nd focal plane. "With an SFP reticle, the spacing for holdover in the reticle is only correct at one magnification, usually the highest setting."

If you change the magnification , the reticle stays constant for visibility but the POI moves. I don't know how much. Need to run with the same magnification for accuracy... Did the OP do that?
 

Tech4

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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.
I have that scope and it is .5 moa
 

jgs8163

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Here's a fun question. The literature I looked at for a Vortex Viper HS-T 6-24x50 says it's 2nd focal plane. "With an SFP reticle, the spacing for holdover in the reticle is only correct at one magnification, usually the highest setting."

If you change the magnification , the reticle stays constant for visibility but the POI moves. I don't know how much. Need to run with the same magnification for accuracy... Did the OP do that?
Hmmm, good point. He mentions “cranking it up 12.25 moa and bangs steel”, I would ASSUME that means he’s using the turret.?! All we’ve got now is a unfinished novel.
 

jdavistx

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I would assume so, but if he's not... I have an older Leupold VX-III 6.5-20x50, SFP. It drove me nuts until I a friend 'splained to me the difference. I once used a lower magnification to sight-in and higher magnifications for long range shots. Not today. Guess we'll have to wait for the last page in the last chapter.
 

Steve gavette

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Here's a fun question. The literature I looked at for a Vortex Viper HS-T 6-24x50 says it's 2nd focal plane. "With an SFP reticle, the spacing for holdover in the reticle is only correct at one magnification, usually the highest setting."

If you change the magnification , the reticle stays constant for visibility but the POI moves. I don't know how much. Need to run with the same magnification for accuracy... Did the OP do that?
My Vortex is the same. But I certainly assumed he was dialing it in and not try to hold a fraction of MOA on a SFP scope @ 900 yds.
 

jdavistx

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My Vortex is the same. But I certainly assumed he was dialing it in and not try to hold a fraction of MOA on a SFP scope @ 900 yds.
As did I. Then I went back to basics. We're dealing with roughly a 5.6 MOA miss @ 900 yards (17.93 MOA calculated vs 12.35 actual - That's about 50" @900 yards.) AB Analytics calculates about 18 MOA based on the available data provided, which is consistent with other inputs. I am also reminded the system shoots 0.3 MOA which translates to 2.8" @900 yards all other things being equal?. What could cause such a massive miss?

It would take really bad data entered into the software (but it's been verified by others here) so it must be something else - mechanical? My hat's off to the guys who suggested looking at the scope. How the scope tracks or my question: If SFP is being used correctly. It's all I can think of. The former would explain it, but a rare occurrence, just like SFP. If it is scope tracking, Vortex should and will replace as it sounds like a recent purchase given their warranty.

SPF an interesting question to me as it messed me up, but by no means the correct answer.

Once elevation is solved, then move on to windage. A 1.25 MOA actual is 11.8," while shooting at a 12" plate @900 yards. If the numbers are incorrect (especially wind), it's a miss.
 

nksmfamjp

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Jan 5, 2004
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if I were betting on this, it seems like mil turrets. I say this because I tried jacking with bc and velocity to get his drops. There were no reasonable changes to get to his actual drops. Then there is the wind. My guess is there was some wind.
 

Its204fast

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May 20, 2020
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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.
If you cannot resolve this, check with Strelok Ballistics Users Group on Facebook Igor is the developer and he is very responsive.
 

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