.308 loads, iPhone, Bullet Flight & a Kestrel 4500

[Vipa]

Hi guys

Just been reading a couple of posts that got me thinking... I have an iPhone with Bullet Flight and Ballistics FTE... bullet flight seems to be the best interface.. I also have a Kestrel 4500NV

What's the best method to 'sync' my ballistics software in the field along with my loads? so that the data out actually matches the conditions and puts the bullet where I want it to go!

Do I mess with the muzzle velocity in the software or start altering BCs etc... ?

Thanks
Paul

Sorry if this is in the wrong section... Mods feel free to move it if it is...

 

[jroberts]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

tag im also interested in this

 

[armydog]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

I sent an email to Kestrel asking is the Horus Atrag Ballistics feature could be added to an older version that did not come with it but still waiting, I think I will have to call to get an answer, hopefully.

 

[HillbillyfromAL]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

The way I do it is to create your profile with all the correct data from your Kestrel. Then start shooting at 100yd intervals checking the real world data against your ballistics program. If it's off at 300 adjust the bullet speed in the profile until it matches. Then continue out to 600yds and if it needs more fine tuning do it but make sure the 300 still matches. Then just keep going. Sometimes 10fps is all that's needed. Once it matches be sure that profile is saved as your zero. Then the next time everything should line up because it will take the new conditions into account. There might be a better way but I don't know it.

 

[JJRawr]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

From what I've read in other posts BC are just a guide and will never be 100% spot on. I guess just trial and error until you find what's working for you. I noticed my 4500 doesn't take the most accurate measurements in the world 100% of the time.

The more equipment you use, the higher possibility it is for mistakes in calculations. That's what happens to me anyways. I'm trying to use the kestrel as only a reference. I don't make adjustments off of my BC. I am trying to learn how to do it without using a bc

 

[HillbillyfromAL]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

BC means Ballisitic Coefficent, not Ballisitic Calcutaor. Kestrel are very accurate pieces of equipment if used properly. If you just put random crap into a ballistic program that's exactly what it will give you in return. Go over to shooterready.com and practice for a while using your ballistic calculator setting up a profile with thier zero parameters, and current conditions. Then you'll be able to visualize everything. The benefits of a ballisitic program are apparent to even the most experienced shooters. They just don't rely on them 100%

 

[JJRawr]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Thanks for the clarification. I'm still learning!

As far as my 4500 not bein accurate I've checked google earth as instructed in my kestrel and it has read - + 50 ft in altitude and a point or two with BP. I dont know why. I guess what I'm getting at is that I'm shooting better using it as a reference to double check. I try not to rely on it

 

[2shoot1kill]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

this is interesting

 

[Vipa]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JJ Rawr</div><div class="ubbcode-body">Thanks for the clarification. I'm still learning!

As far as my 4500 not bein accurate I've checked google earth as instructed in my kestrel and it has read - + 50 ft in altitude and a point or two with BP. I dont know why. I guess what I'm getting at is that I'm shooting better using it as a reference to double check. I try not to rely on it </div></div>

The Kestrel uses air pressure to determine altitude... as air pressure changes constantly, If you don't give it a reference point it will just use the last one in memory (if you've never done it, that will be the factory setting) and will try to calculate your altitude based on current air pressure vs last known altitude...

 

[Kevlars]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Set your reference alt. to zero on your 4500 and use the Density Altitude for adjustment.

Setting your reference altitude to zero will give you station pressure which is more accureate than Barometic pressue as the Baro is corrected Station Pressure for your altitude.

If your calcultor does not accept Density Altitude then use Station Pressure.

 

[HillbillyfromAL]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Good point about the station pressure. Also when you input the pressure into Bullet Flight it will ask if this is absolute pressure and ask that you set the Alt in BF to 0. If you hit the collect conditions from local thing it will have inputed the ALT and you will need to type zero in there. You should just use the kestrel though.

 

[mouse07410]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

I don't understand the question.

1. You go and zero your rifle. Things like bullet weight and BC you should already know from literature (e.g. Bryan Litz book comes to mind) and/or factory cartridge specs.

2. You take from Kestrel the exact weather parameters and key those into "Zero" part of the cartridge profile. This applies to both Ballistic FTE and Bullet Flight. As other posters above mentioned - you want Absolute Pressure from Kestrel (when Altitude is set to 0). Make sure to configure both programs accordingly (what you'll be entering is <span style="text-decoration: underline">not</span> Sea-Level (Corrected) Pressure.

3. You take the Muzzle Velocity measured by a chronograph (or whatever's specified for that factory cartridge - your choice) and key it into the profile.

Done.

4. Now when you get to a (different?) place to shoot - you take the weather from Kestrel and key it in as "Current weather conditions". Calculator will give you its trajectory prediction.

P.S. Lowlight often emphasizes that gadgets are great, but they're best used to hone <span style="text-decoration: underline">your</span> ability to tell the conditions - mostly applicable to the wind. Otherwise, if learned to always rely on e.g. Kestrel being there and faithfully reporting - what happens when there are no more batteries?

 

[Vipa]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mouse07410</div><div class="ubbcode-body">I don't understand the question.

1. You go and zero your rifle. Things like bullet weight and BC you should already know from literature (e.g. Bryan Litz book comes to mind) and/or factory cartridge specs.

2. You take from Kestrel the exact weather parameters and key those into "Zero" part of the cartridge profile. This applies to both Ballistic FTE and Bullet Flight. As other posters above mentioned - you want Absolute Pressure from Kestrel (when Altitude is set to 0). Make sure to configure both programs accordingly (what you'll be entering is <span style="text-decoration: underline">not</span> Sea-Level (Corrected) Pressure.

3. You take the Muzzle Velocity measured by a chronograph (or whatever's specified for that factory cartridge - your choice) and key it into the profile.

Done.

4. Now when you get to a (different?) place to shoot - you take the weather from Kestrel and key it in as "Current weather conditions". Calculator will give you its trajectory prediction.

P.S. Lowlight often emphasizes that gadgets are great, but they're best used to hone <span style="text-decoration: underline">your</span> ability to tell the conditions - mostly applicable to the wind. Otherwise, if learned to always rely on e.g. Kestrel being there and faithfully reporting - what happens when there are no more batteries?

</div></div>

You have misunderstood slightly...

Chronos aren't perfect and BCs (theoretically) are only exatcly at one specific velocity but it would be practically impossible to have a 'dynamic' bc that changed for every fps difference etc... so, even in the best examples, where we have multiple bcs they still have to cover a wide speed range. Therefore, errors will creep in along the way...

If I measured 10 rounds over my Chrony Gamma, took the average, plugged all the data into Bullet Flight including manufacturer quoted bcs, atmospheric data etc and then just dialled in what it told me.... forgetting about windage for now, the chances of the elevation being spot on are pretty slim... I had exactly this scenario recently, bullet flight was 10 clicks out! There was an error somewhere or a combination of errors all ganging up on me...

To get my clicks and impacts to match what bullet flight tells me they should be, I need to take the rough data and match it in the real world.. my question was, what's the best way to do that?

My initial thoughts are...

1. take the rough data, this should get me on paper, or near, and then record tha ACTUAL clicks needed to get the elevation bang on at the given range
2. alter the muzzle velocity in BF until the output matches what has actually happened in the field.
3. repeat for various distances...

It's number 3 that's potentially an issue as, what if altering MV at 500yds then means the output is wrong at 1000 (that you have already adjusted!) which is why I was asking whether it is MV I should be messing about with in BF or the BCs, as I could potentially adjust the output by altering those. That would also enable me to get different results at different ranges as BF uses multiple BCs depending on velocity.

 

[Kevlars]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mouse07410</div><div class="ubbcode-body">I don't understand the question.

1. You go and zero your rifle. Things like bullet weight and BC you should already know from literature (e.g. Bryan Litz book comes to mind) and/or factory cartridge specs.

2. You take from Kestrel the exact weather parameters and key those into "Zero" part of the cartridge profile. This applies to both Ballistic FTE and Bullet Flight. As other posters above mentioned - you want Absolute Pressure from Kestrel (when Altitude is set to 0). Make sure to configure both programs accordingly (what you'll be entering is <span style="text-decoration: underline">not</span> Sea-Level (Corrected) Pressure.

3. You take the Muzzle Velocity measured by a chronograph (or whatever's specified for that factory cartridge - your choice) and key it into the profile.

Done.

4. Now when you get to a (different?) place to shoot - you take the weather from Kestrel and key it in as "Current weather conditions". Calculator will give you its trajectory prediction.

P.S. Lowlight often emphasizes that gadgets are great, but they're best used to hone <span style="text-decoration: underline">your</span> ability to tell the conditions - mostly applicable to the wind. Otherwise, if learned to always rely on e.g. Kestrel being there and faithfully reporting - what happens when there are no more batteries?

</div></div>

You need know one of the following barometric pressure/station pressure,altitude,DA., Different altitudes apply different pressures on the bullet flight. As long as you can get one of these values and have a chart dependent on your muzzle velocity you can calculate where your bullet impact (somewhat).

I think LL was stating that you should not overload yourself with gadgets. However you need some minimal information on your FFP.

 

[mouse07410]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Chronos aren't perfect</div></div>
Which is why it pays to use good equipment.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">and BCs (theoretically) are only exatcly at one specific velocity</div></div>
Not really. I think you're mixing up things. G1 BC provided by manufacturers indeed tend to be less than <span style="text-decoration: line-through">useful</span> accurate across the velocity band of the long range shooting. Which is why books like the one by Bryan Litz "Applied Ballistics" are so valuable - you can find there a reasonably reliable BC for your bullet.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">but it would be practically impossible to have a 'dynamic' bc that changed for every fps difference etc... so, even in the best examples, where we have multiple bcs they still have to cover a wide speed range. Therefore, errors will creep in along the way...</div></div>
IMHO (no offense meant) the above is an example of "paralysis by analysis". IMHO - don't go there.


<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">If I measured 10 rounds over my Chrony Gamma, took the average, plugged all the data into Bullet Flight including manufacturer quoted bcs, atmospheric data etc and then just dialled in what it told me.... forgetting about windage for now, the chances of the elevation being spot on are pretty slim... I had exactly this scenario recently, bullet flight was 10 clicks out! There was an error somewhere or a combination of errors all ganging up on me...</div></div>
The old Computer Science rule: "Garbage In = Garbage Out". If you don't have a good BC and you don't have a reasonably close MV - ...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">To get my clicks and impacts to match what bullet flight tells me they should be, I need to take the rough data and match it in the real world.. my question was, what's the best way to do that?</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
My initial thoughts are...

1. take the rough data, this should get me on paper, or near, and then record tha ACTUAL clicks needed to get the elevation bang on at the given range</div></div>
If - as in the example you brought in yourself - you're 10 <span style="text-decoration: underline">clicks</span> off, you may not even be on paper.

But of course the idea is correct - you compare the actual correction to the one predicted by the calculator.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">2. alter the muzzle velocity in BF until the output matches what has actually happened in the field.</div></div>
And why not altering the BC? That's the problem with not having trusted sources of data. How do you know that BC you're using is more trustworthy than MV you're trying to correct?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">3. repeat for various distances...</div></div>
Usually you get the actual correction for various distances - then you start computing "range cards" playing with both MV and BC (one at a time!) trying to get a combination that gives you the set of corrections closest to what you observed on the targets.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
It's number 3 that's potentially an issue as, what if altering MV at 500yds then means the output is wrong at 1000 (that you have already adjusted!) which is why I was asking whether it is MV I should be messing about with in BF or the BCs, as I could potentially adjust the output by altering those. That would also enable me to get different results at different ranges as BF uses multiple BCs depending on velocity.</div></div>
See above. I'll try to add more later, and hope that Lindy, Bryan Litz, Lowlight and a few others jump in and share their wisdom on this subject.

 

[Dodgefan]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Another poster hinted towards it, IMHO if you are still using G1 BC's you are behind the power curve. G7 is a much better match to the bullets most of us use to shoot long range. Here are some things to try though.

1.If Your chart is too flat only at closer ranges… Lower muzzle velocity and raise BC

2. If Your chart is too flat only at longer ranges…. Raise muzzle velocity and lower BC

3. If Your chart is too flat at all ranges…. Lower muzzle velocity

4. If your chart has too much drop at (closer/longer ranges) do opposite of above

Hope this helps.

 

[Vipa]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mouse07410</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Chronos aren't perfect</div></div>
Which is why it pays to use good equipment.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">and BCs (theoretically) are only exatcly at one specific velocity</div></div>
Not really. I think you're mixing up things. G1 BC provided by manufacturers indeed tend to be less than <span style="text-decoration: line-through">useful</span> accurate across the velocity band of the long range shooting. Which is why books like the one by Bryan Litz "Applied Ballistics" are so valuable - you can find there a reasonably reliable BC for your bullet.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">but it would be practically impossible to have a 'dynamic' bc that changed for every fps difference etc... so, even in the best examples, where we have multiple bcs they still have to cover a wide speed range. Therefore, errors will creep in along the way...</div></div>
IMHO (no offense meant) the above is an example of "paralysis by analysis". IMHO - don't go there.


<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">If I measured 10 rounds over my Chrony Gamma, took the average, plugged all the data into Bullet Flight including manufacturer quoted bcs, atmospheric data etc and then just dialled in what it told me.... forgetting about windage for now, the chances of the elevation being spot on are pretty slim... I had exactly this scenario recently, bullet flight was 10 clicks out! There was an error somewhere or a combination of errors all ganging up on me...</div></div>
The old Computer Science rule: "Garbage In = Garbage Out". If you don't have a good BC and you don't have a reasonably close MV - ...

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">To get my clicks and impacts to match what bullet flight tells me they should be, I need to take the rough data and match it in the real world.. my question was, what's the best way to do that?</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
My initial thoughts are...

1. take the rough data, this should get me on paper, or near, and then record tha ACTUAL clicks needed to get the elevation bang on at the given range</div></div>
If - as in the example you brought in yourself - you're 10 <span style="text-decoration: underline">clicks</span> off, you may not even be on paper.

But of course the idea is correct - you compare the actual correction to the one predicted by the calculator.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">2. alter the muzzle velocity in BF until the output matches what has actually happened in the field.</div></div>
And why not altering the BC? That's the problem with not having trusted sources of data. How do you know that BC you're using is more trustworthy than MV you're trying to correct?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">3. repeat for various distances...</div></div>
Usually you get the actual correction for various distances - then you start computing "range cards" playing with both MV and BC (one at a time!) trying to get a combination that gives you the set of corrections closest to what you observed on the targets.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
It's number 3 that's potentially an issue as, what if altering MV at 500yds then means the output is wrong at 1000 (that you have already adjusted!) which is why I was asking whether it is MV I should be messing about with in BF or the BCs, as I could potentially adjust the output by altering those. That would also enable me to get different results at different ranges as BF uses multiple BCs depending on velocity.</div></div>
See above. I'll try to add more later, and hope that Lindy, Bryan Litz, Lowlight and a few others jump in and share their wisdom on this subject.
</div></div>

Thanks guys, this is what I'm looking for... The more the better!

 

[Vipa]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dodgefan</div><div class="ubbcode-body">Another poster hinted towards it, IMHO if you are still using G1 BC's you are behind the power curve. G7 is a much better match to the bullets most of us use to shoot long range. Here are some things to try though.

1.If Your chart is too flat only at closer ranges… Lower muzzle velocity and raise BC

2. If Your chart is too flat only at longer ranges…. Raise muzzle velocity and lower BC

3. If Your chart is too flat at all ranges…. Lower muzzle velocity

4. If your chart has too much drop at (closer/longer ranges) do opposite of above

Hope this helps.
</div></div>

Excellent, thanks Dodge... The BCs I am using are the ones being imported into Bullet Flight from it's own internal library and althou it does provide multiple BCs, in the case of the SMKs they are G1s..

 

[Vipa]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Ok... I've ordered Bryan's book too

 

[BryanLitz]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

I haven't read the entire thread, so I appologize if this has been said already (although it's important enough to repeat)

If you're trying to match a computer predicted trajectory with actual drops, you must test your scope to see if it's tracking properly. If you dial 25 MOA and the reticle actually moves 23 or 26 MOA, that can be very confusing.

Test this by shooting a 'tall target' at 100 yards. Shoot your 100 yard zero at the bottom of the tall target, then adjust up 25 or 30 MOA and shoot another group. Measure the distance between the groups and calculate the exact MOA that it moved. This can be a very revealing excersise also in terms of verifying the scope is level (did the poi move straight up, or up and to the side?)

Good luck,
-Bryan

 

[BryanLitz]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

I haven't read the entire thread, so I appologize if this has been said already (although it's important enough to repeat)

If you're trying to match a computer predicted trajectory with actual drops, you must test your scope to see if it's tracking properly. If you dial 25 MOA and the reticle actually moves 23 or 26 MOA, that can be very confusing.

Test this by shooting a 'tall target' at 100 yards. Shoot your 100 yard zero at the bottom of the tall target, then adjust up 25 or 30 MOA and shoot another group. Measure the distance between the groups and calculate the exact MOA that it moved. This can be a very revealing excersise also in terms of verifying the scope is level (did the poi move straight up, or up and to the side?)

BTW, this is the topic of Chapter 9: "Getting Control of Sights".

Good luck,
-Bryan

 

[mouse07410]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Thanks, Bryan!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Vipa</div><div class="ubbcode-body">Excellent, thanks Dodge... The BCs I am using are the ones being imported into Bullet Flight from it's own internal library and althou it does provide multiple BCs, in the case of the SMKs they are G1s..</div></div>
Built-in (<span style="font-style: italic">imported from good sources - better than what you would <span style="text-decoration: underline">normally</span> be able to reproduce at home range</span>) multi-band BC in the programs like Bullet Flight and FTE are usually top-notch. There were a couple of exceptions, but in general this rule holds. If uncertain, or if the reality invalidates those numbers - take those from Bryan's book and punch them in manually.

If a BC came from a trusted source - I'd be wary about modifying it, leaning towards peculiarities of my setup that day rather than a mistake in the measurements or processing of the person who supplied those BC to me (not an impossibility, but an improbability).

I'd worry about my own skills, and muzzle velocity. But wait, you said you can't trust your chrono... You see? It's fairly easy to correct one erroneous parameter when you can trust the rest of them, and quite an uncomfortable task if none is really trustworthy.

Dodgefan gave an excellent advice. But it assumes that either the shooter doesn't introduce his own errors, or that shooter's errors are consistent across the board (i.e. you'd repeat exactly the same mistake in exactly the same way next time when you shoot this ammo at the same distance so your POI shift is also consistent).

Bryan, great advice - as usually. But again, the shooter would be a concern: is it the scope that is installed crooked, or the shooter that cants the rifle?

 

[Lindy]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

No ballistic program, however good, will give you a perfect prediction for any given shot at longer distances.

To see why, read Sources of Ballistic Program Inaccuracies

 

[sobrbiker883]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">No ballistic program, however good, will give you a perfect prediction for any given shot at longer distances.

</div></div>

Amen!!

Ballistic FTE using Brian's G7 profiles and DA are damned close. Even shooting over a bulletproof chrono, using a scope with verified tracking, and having solid atmospheric data I've never met a load that tracks 100% through all distances from a 100yd zero to transonic.

The best data and computations will get you damned close (within a couple tenths usually) but I often tweak the velocity to match the field recorded dope inside 5-600a and tweak the BC a little to get the 5-600+ to rectify with each other.

Then when I'm in a different locale of weather and I pop in the DA, I am prepared to note where my round goes, because it more often than not is not exactly where predicted.

Tools help, but until we have laser designated small arms bullets with nano control surfaces misses are gonna happen.



Then there's the trigger control, cheek placement, grip pressure etc......

 

[BirdmanOz]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Does that mean its worth switching the ballistics FTE BC mode to G7 because it is better than their G1? I find their calcs are pretty close. Elevation is out by maybe 1 to 2 mrad clicks at 500 metres. That's still max 10 cm at 500 m. Can't comment on wind effect and the FTE predictions as much yet because I find it the hardest variable to lock down.

 

[mouse07410]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

Birdman, in general my answer would be yes.

Except when FTE has multi-band G1 BC - because it seems that when you tell FTE to use G7 computations on G1 BC, it converts multi-band G1 BC to a single G7 BC. I'm not sure that it's what's happening, but it's worth to keep an eye on.

 

[hrt4me]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">The best data and computations will get you damned close (within a couple tenths usually) but I often tweak the velocity to match the field recorded dope inside 5-600a and tweak the BC a little to get the 5-600+ to rectify with each other.</div></div>

interesting that you have to tweak MV in once instance and then BC in another

 

[VKC]

Re: .308 loads, iPhone, Bullet Flight & a Kestrel 4500

I previously also adjusted the BC & velocity in different programs at different range intervals to match my actual DOPE.

Now I use shooter and don't find any need to adjust the BC, as it has been right on for me. I only adjusted my velocity.

Then I switched to a better rangefinger (vectronix) with a tripod, and found that my prior errors were actually from ranging inaccurately, especially at further distances.

G7 curves with the right velocity and Bryan Litz's measured BCs have been right on within 0.1 mils for me out to 1000 yards or more depending on the caliber.