Trajectory Validation... again. Strelok Pro.

[Racer88]

If you go back to the Everyday Sniper podcast with David Tubb he talks about tuning a rifle using the brake and how brakes have a much larger effect than people realize.

It’s a good interview

Yep. Surprised me!

I'm still learning. Hopefully I never stop learning. SH has been very helpful in accelerating the learning curve.

 

[Nik H]

This thread is why I come here...learn something every day

 

[Racer88]

Well... the difference in POI I saw at the 100 yard range (attributed to the muzzle brake) accounted for 1-1/2 MOA of that 2-1/4 difference at 600 yards. So, that leaves 3/4 MOA unaccounted for. But, that could be other factors, including MV and BC discrepancies, and environmental differences, I suppose.

In any case, it was an interesting and educational experiment!

 

[Nik H]

It seldom is going to be dead on....that is just the way it is. That is why the DOPE book is so critical. As @lowlight said, actual data that you can use to calibrate the parameters is critical.

I had a problem once different than yours but @Skookum provided an answer due to lighting when I zeroed versus lighting when I was shooting. I know check zero EVERY time before I begin.

If you expect that your computer will provide a dead on firing solution, you will be disappointed. It should be reasonably close but that is as best as it gets IMHO.

If you haven't done so, read the weaponized math threads...it works and well

 

[Racer88]

It seldom is going to be dead on....that is just the way it is. That is why the DOPE book is so critical. As @lowlight said, actual data that you can use to calibrate the parameters is critical.

I had a problem once different than yours but @Skookum provided an answer due to lighting when I zeroed versus lighting when I was shooting. I know check zero EVERY time before I begin.

If you expect that your computer will provide a dead on firing solution, you will be disappointed. It should be reasonably close but that is as best as it gets IMHO.

If you haven't done so, read the weaponized math threads...it works and well

I don't expect dead on, of course. Too many variables.

I think within 3/4-MOA at 600 fits the "reasonably close" standard. On steel, that's a hit. For bullseye, it's a small adjustment. And, of course... your own DOPE is the best.

Ultimately, I learned something, which is always a good thing.

 

[SkuseyBoy]

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.

Im hoping you could help me with a little something. its my 1st time posting on here and couldnt figure out how to post to the ballistic app section and this is relatively close to what i am looking for. Im a Brit so im gonna be using meters and mils and such.

So, the problem im having is that my trued dope i have out to 940m, good central hits on 12" plates or smaller all the way out. i cant get those to match Strelok Pro all the way through. i read that its advised to true the ballistic calculator at 600y. my closest true measurement is at 570m/623y.
i adjusted the BC so that strelok pro matches my dope i gathered, but at 940m strelok is 0.4 mils higher than my gathered dope. and 0.2 mils low at 450m.

i believe my speeds are good, shooting a 6.5 creedmoor out of a 26" barrel. 42.4 grains of V555 with a lapua Scenar 139gr. 10 shots on a magnetospeed, avg 2764f/s, SD 4.2, ES of 13.

My gathered dope: Strelok:
100m: Zero 100m: zero
200m: 0.5mils 200m: 0.5
450m: 2.9mils 450m: 2.7
570m: 4.0mils 570m: 4.0
740m: 6.3mils 740m: 6.3
815m: 7.4mils 815m: 7.4
850m: 7.7mils 850m: 8.0
885m: 8.2mils 885m: 8.5
940m: 9.1mils 940m: 9.5

Scope im using is a Delta Optical Stryker HD 4.5-30x56. its exactly 2 1/2 inches from the bore. the barrel twist rate is 1:8.
i have the G7 ballistic coefficient set at 0.273. i think the bc based on choosing the 139grn scenar from the bullet selection is 0.28

i am confused and dont know how to get strelok to match up all the way through my dope. i dont even know if its supposed to be like that anyway.
i would of liked to get trued dope every 100m but a limitation in targets put a stop to that idea.

 

[Lowlight]

You can see how your errors are growing

I need to clean this up to help a little bit, the best way to go about this comparison is to give me your verified data, then give us what Strelok in a better format, but we can work with what you have above

One thing with ranges, public, private, etc, you have to verify the ranges because this can be a point of error. For example, the range we use in Alaska they tell everyone, that is a 700-yard target, well it's 718, not 700.

To adjust the numbers after 570m, you use the BC and manipulate that number. Start with the middle number and then move it in this case, up, as you need less drop with your strelok numbers.

So changing the BC will not change the values close up, like MV does.

Muzzle velocity 600 and in,

BC 800 and out... it will line up.

 

[The King]

You can see how your errors are growing

I need to clean this up to help a little bit, the best way to go about this comparison is to give me your verified data, then give us what Strelok in a better format, but we can work with what you have above

One thing with ranges, public, private, etc, you have to verify the ranges because this can be a point of error. For example, the range we use in Alaska they tell everyone, that is a 700-yard target, well it's 718, not 700.

To adjust the numbers after 570m, you use the BC and manipulate that number. Start with the middle number and then move it in this case, up, as you need less drop with your strelok numbers.

So changing the BC will not change the values close up, like MV does.

Muzzle velocity 600 and in,

BC 800 and out... it will line up.

I'm old...but I've decided to try weaponized math this year during some downtime. Very interesting concept.

I'm developing an unscientific notion that the barrel twist and rifling type have an impact on BC. I would love to see a high end doppler run sometime with different barrel twists. It makes at least theoretical sense to me that the bullet changing surface finish due to rifling engraving would have some outcome.

I have for sure seen ballistic calculators have a nervous breakdown and give you crap numbers, even with hard verified numbers across the board input into them. I have also seen calculators like the Revic PMR that sucked bad when given a G7 number that couldn't have done a better job when given the G1 numbers.

 

[Lowlight]

They already have it, and I have copies, everything affects the BC, MV, twist, etc,

The Weaponized Math doesn't care, it's gravity-based, and there is no bullet.

G1 vs G7 is a fake argument, neither cares, and I have two Revics, and his BR Rangefinder, and Gunwerks software is actually very very good I use both interchangeably that is an academic argument, not a practical one.

 

[_Windrider_]

I'm old...but I've decided to try weaponized math this year during some downtime. Very interesting concept.

I'm developing an unscientific notion that the barrel twist and rifling type have an impact on BC. I would love to see a high end doppler run sometime with different barrel twists. It makes at least theoretical sense to me that the bullet changing surface finish due to rifling engraving would have some outcome.

I have for sure seen ballistic calculators have a nervous breakdown and give you crap numbers, even with hard verified numbers across the board input into them. I have also seen calculators like the Revic PMR that sucked bad when given a G7 number that couldn't have done a better job when given the G1 numbers.

Twist doesn’t have any effect on BC directly. Twist is stability. If a bullet isn’t stable it has more drag which decays velocity which lowers BC. Butvtwist isn’t directly in the BC equation.

 

[Lowlight]

If you look, I am using the Valkyrie in that other post, because the Valkyrie uses a Sierra Bullet, I used a G1 value and they BAND IT, and without any truing the values line up to my real-world data

the G1 vs G7 argument is fake, you can absolutely use both with equal success,

There you can see my inputs for this

 

[st1650]

Kind of curious about what's the best way to manage the data and "truing" especially with big temperature swings.

I started a logbook where I put chrono data from a MS3 every time that I'm going to the range and I put in the day's density altitude and temperature and velocity to try to gather more data to "predict" the velocity on a given day/season.

But then when I go back shooting in the winter, the velocity is much lower, even with temp stable powders like XBR, Varget and H4350.
My local range doesn't go past 550 yards so it's not like I see a big difference in real life but I'd like to get a better foundation and not simply rely of the software because as we all know, garbage in -> garbage out.

My question is
I have Strelok pro that I generally use to manage my guns/profiles because it's quicker and easier to manage and you can write notes specific to a load than my Kestrel 5700. In Strelok, I usually used banded G1 or G7 - haven't seen any real world difference. And once I'm happy with a certain load and profile that I have in Strelok, I'll make a profile in the Kestrel AB and sync it to the 5700 Elite but I use the AB own's curve because in my naivety, I think that paying the extra for the AB Elite, I might as well use their curves since they "should" be more accurate.

I read the other day that it wasn't the greatest idea to use truing and the MV temp table because it might impact the custom curve.
So should I simply keep a book of usual velocities (ie 2700 in -20C and say 2800 in +40C) and simply use 1 velocity value in the kestrel and update it the day that I am shooting or should I stop using the AB custom curves and simply use G1/G7 across the board and if so should I use the MV temp table or just one.

 

[Lowlight]

The Temperature table is a hard avoid, it will screw up a track faster than any other input

Once you true your data it's the software that adjusts it for temperature and the environmental changes. You don't... and honestly, the swings locally are not as big as you think. If you travel, yes you will see big, 1 Mil or more swings but at home on your home range, maybe .3 in changes in a season. If you shoot all year long, you'll see it, but you know, however, if you are bouncing 72 to 92, that swing is not as big as you think, and software can more than manage it

Truing is a necessity because the software is working with averages. But you can have a hard copy home range dope and that will barely change day to day.

 

[SkuseyBoy]

You can see how your errors are growing

I need to clean this up to help a little bit, the best way to go about this comparison is to give me your verified data, then give us what Strelok in a better format, but we can work with what you have above

One thing with ranges, public, private, etc, you have to verify the ranges because this can be a point of error. For example, the range we use in Alaska they tell everyone, that is a 700-yard target, well it's 718, not 700.

To adjust the numbers after 570m, you use the BC and manipulate that number. Start with the middle number and then move it in this case, up, as you need less drop with your strelok numbers.

So changing the BC will not change the values close up, like MV does.

Muzzle velocity 600 and in,

BC 800 and out... it will line up.

sorry it was a lot clearer when i typed it out didnt realise it would all bunch up like that.

Verified dope:
100m: Zero
200m: 0.5mils
450m: 2.9mils
570m: 4.0mils
740m: 6.3mils
815m: 7.4mils
850m: 7.7mils
885m: 8.2mils
940m: 9.1mils

Strelok:
100m: zero
200m: 0.5 mils
450m: 2.7 mils
570m: 4.0 mils
740m: 6.3 mils
815m: 7.4 mils
850m: 8.0 mils
885m: 8.5 mils
940m: 9.5 mils

i ranged the targets with a vortex razor hd 4000 and most were within 2-3m. at the time i didnt think it was really important to right down the exact range i just rounded to the nearest 5m.

and to confirm adjust the bc for 740m and up. and the muzzle velocity number for below that.

 

[Lowlight]

Have you tried adjusting the BC so the 940M matches ?

That is your biggest error so I would align that number

 

[SkuseyBoy]

Have you tried adjusting the BC so the 940M matches ?

That is your biggest error so I would align that number

ok i matched the bc to true the 940m on strelok to my verified data. and seem to be going around in circles changing bc to match the 940m and then changing mv to get the closer distances aligned but throwing the far ones out again.

original strelok bc 0.29

verified data (2764f/s)
100m: Zero
200m: 0.5mils
450m: 2.9mils
570m: 4.0mils
740m: 6.3mils
815m: 7.4mils
850m: 7.7mils
885m: 8.2mils
940m: 9.1mils

new strelok data (2712f/s and 0.313 bc)

100m: Zero
200m: 0.5mils
450m: 2.7mils
570m: 4.0mils
740m: 6.1mils
815m: 7.2mils
850m: 7.7mils
885m: 8.2mils
940m: 9.1mils

do i just keep adjusting the mv and bc until 450m, 740m and 815m all match up?

 

[Lowlight]

I would leave it,

That .2 at 400/700 is nothing, and each number on either side matches

Looks good to me, call it a day and drive on, I highly doubt you will miss something at 400/700 with a .2 variation

 

[SkuseyBoy]

I would leave it,

That .2 at 400/700 is nothing, and each number on either side matches

Looks good to me, call it a day and drive on, I highly doubt you will miss something at 400/700 with a .2 variation

good point haha. Thank you very much for the help bud would of been going around in circles otherwise

 

[st1650]

The Temperature table is a hard avoid, it will screw up a track faster than any other input

Once you true your data it's the software that adjusts it for temperature and the environmental changes. You don't... and honestly, the swings locally are not as big as you think. If you travel, yes you will see big, 1 Mil or more swings but at home on your home range, maybe .3 in changes in a season. If you shoot all year long, you'll see it, but you know, however, if you are bouncing 72 to 92, that swing is not as big as you think, and software can more than manage it

Truing is a necessity because the software is working with averages. But you can have a hard copy home range dope and that will barely change day to day.

And is there any advantage in using the AB customer drag vs g1/g7 or is it not necessary anymore vs years ago when the data wasn’t perhaps as accurate

 

[Lowlight]

I dislike the custom curves,

Those are HIS Custom curves, not yours, if you adjust the BC as I said, you just created a user-editable custom curve

What do you think a Custom Curve is ?

it's just an average with a few more data points. It has nothing to do with your load or you it's their data,

And you can't adjust it, it's locked

 

[JAS-SH]

In my recent experience 100 yard zero is where everything starts to go south. I looked at you targets. Your shots are mostly low. So were mine by the way, don't take it personally.

First, You can forget windage for the moment, but you have to take every shot you made in the two different configurations and AVERAGE the elevation for each to the point of aim. Use calipers if you have them. It's that critical.

Second, Do the same at 300 yards. This is the only thing that will give you a true zero - in inches. That is the only true measure of both drop and velocity. Chronos can be wrong. Software might be off with G7, etc.

How do a true zero? use software that will do it Hornady 4DOF or, make a chart that goes in one yard increments. and find the zero yardage that matches your average. Say the average is .3 inches low. Find the yardage on the software where that is. That's your "Zero Range".

A .3 inch error in 100 yard zero is at the very minimum .6 at 200 and so on, etc. It's always larger than that because of dispersion.

Just because a manufacturer says "this is the BC" that doesn't mean it's YOUR rifle's BC. All rifles are slightly different when it comes to internal ballistics. That's why BC adjustments are made at longer ranges, when it becomes more important that velocity.

Garbage in Garbage out...

Start with that.

 

[iceng]

Ill echo that having a valid zero, and correct distance is key. Your zero should be spot on, not biased high / low.
I tried to help a guy once who zeroed on a 100y range, but was using meters. "Yeah they are close enough, it should be fine". At sub 4 or 500m, yeah probably, but at 1000m, not so much.