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Trajectory Validation... again. Strelok Pro.

Racer88

Racer88

Firearms Pedant
Full Member
Minuteman
    • Nov 10, 2018
    1,160
    1,607
    #1
    Alrighty... another thread about Trajectory Validation. It seems that the consensus is that if you have a true MV (determined by a good chrono), that you should true the BC in the Strelok app. There is also a consensus that beyond 500 - 600 yards, you should true the BC.

    That said... I recently used some (factory) Berger Match Target Hybrid ammo at 600 yards. Strelok told me to use 56 clicks of elevation.
    Trajectory-Validation-1.jpg



    I ended up correcting to 47 clicks of elevation. That's a pretty big difference. A ~2-1/3 MOA difference. (Yes... I validated and corrected my turret click value with a tall target test a while back.)

    Trajectory-Validation-2.jpg



    So, if I true MV, it's a difference of 213 fps! (The original MV I was using was calculated with a MagnetoSpeed.)

    Trajectory-Validation-3.jpg



    But, if I true the BC, it goes from 0.311 (G7) to 0.752! That's a huge difference. Is the trued BC still G7? Or is it reverting back to G1 drag model?

    Trajectory-Validation-4.jpg


    So, what gives? Thanks!
     

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    #6
    It does appear based on your picture that your vertical dial on your scope is Set to .244 were your horizontal says .25. Am I reading that correctly?
     

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    #7
    Tree said:
    It does appear based on your picture that your vertical dial on your scope is Set to .244 were your horizontal says .25. Am I reading that correctly?
    Click to expand...

    The post is hard to read because of all the pics. But he says he used a tall target to validate the tracking correction to .244
     
    #8
    Tree said:
    It does appear based on your picture that your vertical dial on your scope is Set to .244 were your horizontal says .25. Am I reading that correctly?
    Click to expand...

    Yes... I did a "tall target test" elevation click value validation. Twice. The results were exactly the same to 3 decimal points. Usually, there is no need to do a click value validation on the windage (horizontal) turret.
     
    #12
    Since you are truing, your zeroing weather should be the same as your shooting weather. So make sure zeroing weather is turned off (matches current weather).
     
    #14
    BigPineyTradingPost said:
    I saw the same post of Facebook. Seems like he needs to start from scratch or use another ballistic computer to check against. Then again, I don’t use clicks.
    Click to expand...

    I don't count clicks, either. But, I used it in my description, because of the turret click value discrepancy.

    That field in Strelok can be toggled between "clicks" and "1-3/4" format. I normally use the "1-3/4" format, because it's way easier than counting clicks. :) But, I thought "clicks" would translate better on the forum post. Perhaps not. :)
     
    #16
    Sometimes the simplest answer is the right one, your scope isn't tracking properly.

    It could be a lot of things. Is the zero off? Is the zero target really at 100yds exactly?

    You said you did a tall target test, how tall? How much elevation did you go through?

    I think the one reliable piece of data is the MV.

    Pick a system of measurement and stick with it. If your scope is MOA then everything is in minutes. Stop with the clicks thing, clicks have no meaning.
     
    #17
    LawnMM said:
    Sometimes the simplest answer is the right one, your scope isn't tracking properly.

    It could be a lot of things. Is the zero off? Is the zero target really at 100yds exactly?

    You said you did a tall target test, how tall? How much elevation did you go through?

    I think the one reliable piece of data is the MV.

    Pick a system of measurement and stick with it. If your scope is MOA then everything is in minutes. Stop with the clicks thing, clicks have no meaning.
    Click to expand...

    Zero is at 96.28 yards, exactly. :) I measured it with a tape, because I didn't trust the "100 Yards" sign at the sheriff's range where I shoot. And, having the correct range distance is critical in the Tall Target Test. That's why the zero distance in my Strelok app is 96 yards. Strelok doesn't allow the fraction (.28) in the zero distance.

    For the tall target test, I went up 20 MOA. That's as far as I could go with the target frame available at my local range. I ran the test twice and came up exactly the same to three decimal points.

    See my previous comment about "clicks." Believe me, I understand, and I do not count clicks in the field. LOL! I dial MOA. I just toggled that field in Strelok to show clicks instead of the "1-3/4" format, which is what I use. I thought it would be easier to understand here, since most of you guys use MILs. So, yeah... Strelok told me to dial up 14 MOA (56 clicks). I ended up dialing it back (after the first sighter) to 11-3/4 MOA (47 clicks).

    I do everything in "minutes" (MOA) when it comes to dialing turrets, measuring POI / POA differences, making corrections, etc. THAT is not the issue here. Something ELSE is the issue. I'm trying to figure it out.
     
    #18
    When I calculate a similar cartridge but slightly higher BC and your environmentals, I get very close to the same solution as your first one. I have almost the same drop in inches as you. Your correction makes me think something in your scope or zero is off (as LawnMM said above). Your first firing solution should be correct or very close.
     
    #19
    Skip the App for try dope and go to weaponized math it’s easier and works better

    This is the problem with software today and how people with no foundation use it.

    You put in the basic information that all software says it needs, the includes MV and BC but when you go to shoot it the variations from person to person varies widely. There are too issues or potential for operator error. On top of that, they want to change the MV as it’s the only way it can true the data. The problem is the amount of change like noted, 200+ FPS give or take which in the long run and over time and differences in location will screw with your data.

    So we say true the BC to balance the curve and not throw all the adjustments to one side.

    But you’re operating blind because you are using unverified data that turns out to be wrong by a wide measure. The software has flourishes and it corrupts the data, what makes it worse, every software is different so the changes in Strelok are not the same as the changes in AB. It’s unregulated, forcing to do it twice, and you still have to true it.

    You have no starting point, and no way to know if you are right, until you shoot it for record, which forces you to do it twice.

    Enter weaponized math,

    Al, you need is the drop at one range and you’ll probably never be off any given range more than .2 or .3 vs these .7 cgphanges as noted here.

    The weaponized math works better easier after which you can move the data to more robust software.

    Forget try dope with software, use our method it’s better.
     
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    #20
    lowlight said:
    Skip the App for try dope and go to weaponized math it’s easier and works better

    This is the problem with software today and how people with no foundation use it.

    You put in the basic information that all software says it needs, the includes MV and BC but when you go to shoot it the variations from person to person varies widely. There are too issues or potential for operator error. On top of that, they want to change the MV as it’s the only way it can true the data. The problem is the amount of change like noted, 200+ FPS give or take which in the long run and over time and differences in location will screw with your data.

    So we say true the BC to balance the curve and not throw all the adjustments to one side.

    But you’re operating blind because you are using unverified data that turns out to be wrong by a wide measure. The software has flourishes and it corrupts the data, what makes it worse, every software is different so the changes in Strelok are not the same as the changes in AB. It’s unregulated, forcing to do it twice, and you still have to true it.

    You have no starting point, and no way to know if you are right, until you shoot it for record, which forces you to do it twice.

    Enter weaponized math,

    Al, you need is the drop at one range and you’ll probably never be off any given range more than .2 or .3 vs these .7 cgphanges as noted here.

    The weaponized math works better easier after which you can move the data to more robust software.

    Forget try dope with software, use our method it’s better.
    Click to expand...

    I want to be sure I'm following you (be patient). It seems that you are suggesting to just gather my own "DOPE" by measuring the actual bullet drop at various distances. Or, am I misunderstanding? I understand that would be the best way. Nothing beats real world results and having a simple "DOPE" chart. Is that right?

    My issue is the availability of ranges to do that. There are actually none in my area. The only range in my county is at the sheriff's training range, which is open 1 weekend a month with a fixed shooting distance. On Saturday, it's 100 (actually 96 yards). On Sunday, it's 200 (actually 196 yards). Every 3rd month, on Sunday it's 300 yards (an actual 300 yards!).

    Other ranges are 1.5 - 2++ hours drive away. And, as far as I know, the shooting distances are fixed, as well.

    Thanks for chiming in!
     
    Last edited:
    #22
    Given the replies, I'm reluctant to revive this thread. ? :ROFLMAO:

    OK... Yeah... gathering my own DOPE at various range intervals would be the best. I don't have much opportunity to do that with the dearth of ranges in my area. But, I guess I can say I gathered my DOPE for 600 yards, eh? :D

    I was curious what other calculators might come up with. So, I used the Hornady 4DOF online ballistic calculator. It came up with 13-MOA. By way of comparison, Strelok came up with 13-3/4-MOA. My actual come-up was 11-3/4-MOA.

    For the Hornady 4DOF calculator, I input the correct environmentals.

    1578107656285.png


    I ran it through Ballistics ARC on my phone. It came up with 13-MOA, as well.

    1578108391652.png


    One thing I forgot to mention. When I zeroed my rifle, it was with the stock muzzle brake. At the 600-yard match, they don't allow muzzle brakes. So, that day, I shot without it. Is it possible removing the brake changed it by that much?

    If so, I need to do a zero offset for "no brake." Eh?

    Thanks. When I can access a range with multiple target distances, I can gather my own DOPE for all those distances. I promise! ?
     
    #23
    I'm betting you've got an equipment issue. I would verify the scope internal travel is accurate. If you can use your reticle vs your turrets to verify drop data you could solve this (or do a tall target test). By chance are you using vertically split scope rings?
     
    #27
    Dthomas3523 said:
    Check your zero without the brake. I’m sure you’ll find your missing elevation.
    Click to expand...

    "Welp!" You were right! Mystery solved, and I feel a little dumb. At least I know my inputs were all correct.

    Bearing my ballistic soul, so be gentle! ;)

    So, I started by putting the brake ON and re-zeroing the rifle with the new Berger ammo (center bull). And, then shot a few more groups.

    Berger Target 1 groups.jpg


    Then, I got some new velocity data with the Magnetospeed and shot some more groups at the new zero (brake still on).

    Berger Target 2 groups.jpg


    Then I took the brake off and shot a group on the center bull. Shazam! It shot HIGH, just like it did at the 600 yard match. And, not just a little high. A lot higher! Honestly, I expected a LITTLE shift in the POI would be likely when I removed the brake at the 600 yard match. But, I didn't expect that much.

    Berger Target 3 groups no brake.jpg


    Anyway, it was an interesting exercise today. So, now I can create another ammo profile in Strelok with the "No Brake" label and an offset.

    Thanks to all who commented! ?
     
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    #33
    Dthomas3523 said:
    Same principle as a barrel tuner or strapping on a magnetospeed.
    Click to expand...

    Certainly makes sense... which is why I have a pic rail mount for my Magnetospeed. :) But, for SOME reason, the notion of the brake having THAT much of an effect escaped me. ? So, feeling a bit embarrassed.

    But, at least I know my inputs were correct. And, I don't need to do any trajectory validation... yet. :)
     
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    #34
    Racer88 said:
    Certainly makes sense... which is why I have a pic rail mount for my Magnetospeed. :) But, for SOME reason, the notion of the brake having THAT much of an effect escaped me. ? So, feeling a bit embarrassed.

    But, at least I know my inputs were correct. And, I don't need to do any trajectory validation... yet. :)
    Click to expand...

    Many times, you’ll still see some slight POI change in the opposite direction of the magnetospeed even with the pic rail.

    It’s much smaller change. But with the bayonet right under the bore that close, there is some impact shift.
     
    #36
    Okay, if you're shooting under 1200 yards don't act like your shooting a mile with these apps. You got a measured chronograph speed and a reliable BC. Your speed has a standard deviation but you need approx. 30 shot sample to get into the 90% confidence ballpark. So, like I usually only have a 10 shot string to estimate MV before validating with Strelok. Statistically speaking, I'm not totally sold on the MV compared to a reliable BC. Thus, I don't have a problem with using velocity rather than BC if Strelok's calculation is within 3% of my starting MV. The standard is now 1/10th mil or 1/3rd MOA accuracy for most of us. That is just the mechanical dope before pulling the trigger.
     
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    #37
    Sorry. It cost alot of extra work and rounds on your part, but I did learn alot of stuff about strelok pro, and about ballistics

    Not sarcastic, thanks for taking the time.
     
    #38
    TACC said:
    Sorry. It cost alot of extra work and rounds on your part, but I did learn alot of stuff about strelok pro, and about ballistics

    Not sarcastic, thanks for taking the time.
    Click to expand...

    Ammo's for shootin'! ?

    I'm a science nerd, so I dig this stuff and trying to figure it out.
     
    #39
    The apps are fine for learning but getting into the actual ballistics can be a little daunting for some. This is why we should use our brain too. The simple math mentioned above is verified and, I for one, am glad it is being promoted as it is. At one time 1200 yards was considered long range because these old formulas start to fall apart past that range. Now, I don't like AB verifying at its recommended ranges because it may not be practical for a lot of people. AB is really pushing the envelope with these old formulas. It is seriously bloated software. Strelok on the other hand is really very straight forward. But none of these apps come with a disclaimer that the technology is really old. Like WWI old.
     
    #41
    dustingaunder said:
    Copy your load in Strelok and make one with MB on and one with MB off. Then you can zero with one of them and put in an offset on the other. Select appropriate load and it’ll correct it for you in the solution.
    Click to expand...

    Yep! Exactly what I did. Strelok's offset feature is pretty nifty.
     
    #45
    seansmd said:
    It's in the post above not from me, and you send to agree with it so I thought you knew! ?
    Click to expand...

    Oh! Sorry. MB = muzzle brake. Duh. I was reading your comment in isolation and "MB" escaped me.

    So... I'd make a duplicate of the load I used for my zero. Then add the label "No MB (muzzle brake)" and change the zero offset. That way I can just load the profile that applies (am I using the muzzle brake or not) and have my calculations work.
     
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    #46
    Racer88 said:
    Oh! Sorry. MB = muzzle brake. Duh. I was reading your comment in isolation and "MB" escaped me.

    So... I'd make a duplicate of the load I used for my zero. Then add the label "No MB (muzzle brake)" and change the zero offset. That way I can just load the profile that applies (am I using the muzzle brake or not) and have my calculations work.
    Click to expand...
    Haha, I forgot that as well, sorry!
     
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