What ballistics app are you using on your mobile device? and an Applied Ballistics specific program question.

mcb

mcb

Member
Joined
Feb 19, 2008
Messages
8,738
Location
North Alabama
With Strelok no longer available (I am stuck on version 6.3.4 on an old phone, current version 7.1.9) due to the war in Ukraine I am looking for another ballistic app. For those that have a ballistic app on their phone what are you using?

For the price Strelok really did everything I really needed, but I am serious considering spending the $30 on Applied Ballistics to get the enhanced drag models for all the bullets they have tested. For anyone that has the program is there any chance that you can actually see the coefficient of drag vs velocity tables for these bullets that Applied Ballistics has done their radar studies on?

I have gone into a pretty deep dive into ballistics modeling and the most interesting part of that is the drag models used. The simulation is pretty straight forward but the drag modeling is where things get interesting. I finally have the Gx models nailed down and even went so far as to have written my own simple calculator in Python but it was focused on getting the drag model and ballistic coefficient right and does not have all the bells and whistles the real apps have. This is why I asked about Applied Ballistics drag models as I would love to compare those drag coefficients to the Gx models that are more traditionally used.

Thoughts? Suggest. All appreciated.
 
mcb said:
With Strelok no longer available (I am stuck on version 6.3.4 on an old phone, current version 7.1.9) due to the war in Ukraine I am looking for another ballistic app. For those that have a ballistic app on their phone what are you using?

For the price Strelok really did everything I really needed, but I am serious considering spending the $30 on Applied Ballistics to get the enhanced drag models for all the bullets they have tested. For anyone that has the program is there any chance that you can actually see the coefficient of drag vs velocity tables for these bullets that Applied Ballistics has done their radar studies on?

I have gone into a pretty deep dive into ballistics modeling and the most interesting part of that is the drag models used. The simulation is pretty straight forward but the drag modeling is where things get interesting. I finally have the Gx models nailed down and even went so far as to have written my own simple calculator in Python but it was focused on getting the drag model and ballistic coefficient right and does not have all the bells and whistles the real apps have. This is why I asked about Applied Ballistics drag models as I would love to compare those drag coefficients to the Gx models that are more traditionally used.

Thoughts? Suggest. All appreciated.
Click to expand...
I still use strelok pro, just have to download from a 3rd party.
 
Applied Ballistics on the phone isn't as user friendly (IMHO) as Strelok was, but it's very good. Better yet is AB on a Kestrel.
 
Hornady 4DoF is a bit more user friendly than AB Mobile, but both of these work well.

I’m not aware of any way to see the Cd vs. Mach No. curve corresponding to the CDM’s.
 
Varminterror said:
Hornady 4DoF is a bit more user friendly than AB Mobile, but both of these work well.

I’m not aware of any way to see the Cd vs. Mach No. curve corresponding to the CDM’s.
Click to expand...

Yeah thinking about it there is no way AB could afford to show those curves without someone just copying them and putting that data into their own solver. I was watching videos on AB site and even Bryan admits there is nothing all that special about AB's ballistics solvers, what makes AB special is all the work they put into creating the CDM for each projectile. In theory we could probably back out the CDMs from the resulting ballistic tables for a particular bullet if I was really curious enough.
 
Last edited:
On a related subject why is the Kestral 5 series with Applied Ballistics so much more expensive than the version without it? I can get AB on my phone for $30 but it cost at least $300 to get it on a Kestra 5700? Am I missing some something other than just having all that data/sensors in one package instead of two?
 
mcb said:
In theory we could probably back out the CDMs from the resulting ballistic tables for a particular bullet if I was really curious enough.
Click to expand...

This should actually be pretty straight forward - you could even code in Python to derive the incremental BC's against the Mach No. curve, basically deriving the curved regressions by numerical method. You could either use a CDM trajectory to true up your own CDM Cd vs. Mach curve, or use a true trajectory to derive your own curve. A lot of work to get to a stepped then smoothed curve, but doing so might allow you to derive your own arithmetic device to build CDM's for other bullets or at other speeds.

mcb said:
On a related subject why is the Kestral 5 series with Applied Ballistics so much more expensive than the version without it? I can get AB on my phone for $30 but it cost at least $300 to get it on a Kestra 5700? Am I missing some something other than just having all that data/sensors in one package instead of two?
Click to expand...

Largely because folks will pay for it. But we have to remember, the $30 we're paying for an app is just a software license, whereas we're installing it onto a $1000 device with great processing capacity. It's a little frustrating that Kestrel raised their software upgrade price so much in the last few years - they've kept it within spitting distance of the same total cost to buy a Ballistics model (formerly Sportsman) and upgrade to Elite software vs. buying the Elite up front, which has meant the software upgrade has increased in cost by 50% in the last few years... For the same software... Because folks will pay it...
 
Varminterror said:
This should actually be pretty straight forward - you could even code in Python to derive the incremental BC's against the Mach No. curve, basically deriving the curved regressions by numerical method. You could either use a CDM trajectory to true up your own CDM Cd vs. Mach curve, or use a true trajectory to derive your own curve. A lot of work to get to a stepped then smoothed curve, but doing so might allow you to derive your own arithmetic device to build CDM's for other bullets or at other speeds.



Largely because folks will pay for it. But we have to remember, the $30 we're paying for an app is just a software license, whereas we're installing it onto a $1000 device with great processing capacity. It's a little frustrating that Kestrel raised their software upgrade price so much in the last few years - they've kept it within spitting distance of the same total cost to buy a Ballistics model (formerly Sportsman) and upgrade to Elite software vs. buying the Elite up front, which has meant the software upgrade has increased in cost by 50% in the last few years... For the same software... Because folks will pay it...
Click to expand...
Fudd-like question here...

Is there any practical way to calculate a more accurate BC by using G1 out to say 400 yards by averaging BC's at intervals, understanding that drag curves might not be predictive?
 
luv2safari said:
Fudd-like question here...

Is there any practical way to calculate a more accurate BC by using G1 out to say 400 yards by averaging BC's at intervals, understanding that drag curves might not be predictive?
Click to expand...

It is certainly possible but without a lot of shooting at various ranges or a good radar that can track the bullet a long ways down range it's hard to get the data you need to calculated various BC's for the various velocity ranges. Sierra likes to publish multiple G1 BC's for different velocity ranges for some of their bullets and I am pretty sure a few other manufactures do the same. That said for most of our modern rifle bullets you usually get a better fit just using a G7 BC. Programs like Strelok know how to take multiple BCs and the associated velocity ranges and create the smooth "semi-custom" drag function.

The closest I have come to this was to shoot my 22 LR at 25, 50, 75, 100, 125, & 150 all with the exactly the same hold and 25 yard zero and no adjustment to the scope. I measure the drop to each group center at each range and used that drop data to tweak the BC and velocity in Strelok until I minimized the error at all the ranges. In theory I could have done that with more than one BC but the velocity does not change much over that short range so I am not sure how much better it would have made things. Just adjusting the BC and muzzle velocity I got the drop error down to an average ~2.2% and called that good enough.
 
mcb said:
It is certainly possible but without a lot of shooting at various ranges or a good radar that can track the bullet a long ways down range it's hard to get the data you need to calculated various BC's for the various velocity ranges. Sierra likes to publish multiple G1 BC's for different velocity ranges for some of their bullets and I am pretty sure a few other manufactures do the same. That said for most of our modern rifle bullets you usually get a better fit just using a G7 BC. Programs like Strelok know how to take multiple BCs and the associated velocity ranges and create the smooth "semi-custom" drag function.

The closest I have come to this was to shoot my 22 LR at 25, 50, 75, 100, 125, & 150 all with the exactly the same hold and 25 yard zero and no adjustment to the scope. I measure the drop to each group center at each range and used that drop data to tweak the BC and velocity in Strelok until I minimized the error at all the ranges. In theory I could have done that with more than one BC but the velocity does not change much over that short range so I am not sure how much better it would have made things. Just adjusting the BC and muzzle velocity I got the drop error down to an average ~2.2% and called that good enough.
Click to expand...
What I shoot doesn't appear in G7 BC listings. My question was mostly out of curiosity, and I can just shoot 50 yard intervals to 400 or so yards, but that eats up a lot of my Big Game powder that can now be found only in 8lb lots. I find I can get "close enough" with my ancient Lee Shooter Ballistics program. I would like to get my 22-250 dead on at any given range out to 400 yards, however. I use my small supply of Big Game in my '06, 22-250, and 9.3X62.
 
luv2safari said:
Fudd-like question here...

Is there any practical way to calculate a more accurate BC by using G1 out to say 400 yards by averaging BC's at intervals, understanding that drag curves might not be predictive?
Click to expand...

Yes, ish, but…

Are you shooting a true G1 bullet? At low speeds?

400 yards really isn’t so far that the error between a true G1 bullet and it’s predicted trajectory will be very different, UNLESS you’re crossing transonic boundary (aka, low speed and falling near or below 1200fps before 400). If we’re getting errors at 400 with a common bottleneck cartridge (mach 2+), then we have some input wrong in the calculator - it won’t be because of Cd errors between a single BC model and a curve model.

I use multi-BC function with a few of my rifles, but I’m shooting well past 1000 with this. I’ll mention here, I’ve made impacts out to 2900 yards with just a single BC input, not even using a CDM. I say all of that just to give confidence that chasing a curve for 400yrds isn’t likely going to be fruitful, UNLESS you’re shooting something like 22LR, 9mm, or 45-70 with a low BC G1 profile bullet where you’re slipping transonic within the 400yrds.

So there IS a practical means of doing so, but I wouldn’t say there is a practical NEED to do so.
 
Varminterror said:
Yes, ish, but…

Are you shooting a true G1 bullet? At low speeds?

400 yards really isn’t so far that the error between a true G1 bullet and it’s predicted trajectory will be very different, UNLESS you’re crossing transonic boundary (aka, low speed and falling near or below 1200fps before 400). If we’re getting errors at 400 with a common bottleneck cartridge (mach 2+), then we have some input wrong in the calculator - it won’t be because of Cd errors between a single BC model and a curve model.

I use multi-BC function with a few of my rifles, but I’m shooting well past 1000 with this. I’ll mention here, I’ve made impacts out to 2900 yards with just a single BC input, not even using a CDM. I say all of that just to give confidence that chasing a curve for 400yrds isn’t likely going to be fruitful, UNLESS you’re shooting something like 22LR, 9mm, or 45-70 with a low BC G1 profile bullet where you’re slipping transonic within the 400yrds.

So there IS a practical means of doing so, but I wouldn’t say there is a practical NEED to do so.
Click to expand...
As I delve into this a bit more I agree. It would be something for me to fool around with and experiment some. I'd like to see just how far I can reach with a 22-250 and a 9.3X62 and hit small targets. I limit my shots hunting big game to 350 yards, maybe 400 if all conditions are right. BUT, I can load ammo here and run down the ditch road 7 minutes and shoot out to 800 yards. Any farther makes me travel 15-20 minutes, and I can shoot for miles. Our big game herds crashed, and I've not drawn a resident tag for anything the last three seasons. I'll find some recipes for shot up targets.

It would be recreation to try my sporting rifles at what for me are extreme distances. I might risk my chronograph and shoot through it at somewhat longer distances.
 
luv2safari said:
It would be recreation to try my sporting rifles at what for me are extreme distances.
Click to expand...

You won’t need downrange velocities to true your BC. Measure muzzle velocity with your Chronograph, or in lieu of a chrony, use a 400-600yrd target result (shorter for slower, lower BC rounds) to true your muzzle velocity, then shoot at 90% of your transonic distance, often around 900-1100yrds (shorter for your 22-250, and maybe for your 9.3x62) and use that target result to true your BC.

The first half of this works because the velocity is really dominating the flight at short range, so we can have relatively high BC errors and not see much sensitivity in 400-500yrd impacts, but high sensitivity to velocity. As an example, I put the wrong BC into my calculator for my 22-250 load with 55 Vmax’s, changing from .25G1 to .30G1 - a relatively huge error - only meant 2 clicks in my scope… alternatively, changing velocity by 30fps changed the result by a click, so <1% error velocity meant 1 click, 0.1 mils, but 10% BC velocity also meant 1 click… high sensitivity to velocity, not so much to BC.

But at 725 (transonic boundary for my 22-250), that shift from .25G1 to .3G1 means 1.6mils, but those 30fps only mean 0.1 mil shift… huge dependence upon BC, less on velocity.
 
Varminterror said:
You won’t need downrange velocities to true your BC. Measure muzzle velocity with your Chronograph, or in lieu of a chrony, use a 400-600yrd target result (shorter for slower, lower BC rounds) to true your muzzle velocity, then shoot at 90% of your transonic distance, often around 900-1100yrds (shorter for your 22-250, and maybe for your 9.3x62) and use that target result to true your BC.

The first half of this works because the velocity is really dominating the flight at short range, so we can have relatively high BC errors and not see much sensitivity in 400-500yrd impacts, but high sensitivity to velocity. As an example, I put the wrong BC into my calculator for my 22-250 load with 55 Vmax’s, changing from .25G1 to .30G1 - a relatively huge error - only meant 2 clicks in my scope… alternatively, changing velocity by 30fps changed the result by a click, so <1% error velocity meant 1 click, 0.1 mils, but 10% BC velocity also meant 1 click… high sensitivity to velocity, not so much to BC.

But at 725 (transonic boundary for my 22-250), that shift from .25G1 to .3G1 means 1.6mils, but those 30fps only mean 0.1 mil shift… huge dependence upon BC, less on velocity.
Click to expand...
Here is what Lee Shooter listed for my 250gr Accubond load at my average velocity. The Ballistic Tip and Accubond have the same BC.
pVuh4CK.jpg

wiJkjQJ.jpg
 
@luv2safari - looking at those bullets, finding a G7 BC may improve your predicted trajectory accuracy over the G1model, but to see that table, you would true your BC at 900 and be groovy.
 
I’ve only used the Berger Ballistic calculator of similar, I don’t find them particularly accurate. Not sure what’s up with that. I always find myself correcting at the range beyond the suggested moa.
 
The more accurate I am at entering the most precise data I can, the more I generally get out of any of them.

I think one could learn decades worth of conditional corrections, from live fire, in 30 min worth of playing with the 4DOF app.

Not that it does anything to help reading conditions but it will set some off the variables for you, at the rage.
 
JFrank said:
I’ve only used the Berger Ballistic calculator of similar, I don’t find them particularly accurate. Not sure what’s up with that. I always find myself correcting at the range beyond the suggested moa.
Click to expand...

I'd bet dollars to doughnuts the error is between physical altitude as an input on the site vs. Density Altitude. Berger's site calculator isn't very clear that the "Altitude" for their inputs is actually "Density Altitude," not physical altitude. Inputting my physical altitude, right now, and comparing against the conditions I shot on Sunday with my well-trued and proven calculator (thousands and thousands of shots confirmed against that trajectory), I get 1, 2, 3, and 4 tenths mils error for 7, 8, 9, and 1000yrds. If I input the correct Density Altitude into the "Altitude" box on Berger's site, the trajectory comes perfectly in line with what StrelokPro kicks out for my known true trajectory. And vise versa, if I put my physical altitude into StrelokPro instead of Density Altitude in the DA box, then I get the exact same trajectory (down to the 1/100th mil) as I get from Berger's site if I use physical altitude on their site as well...

So it's a misidentification on their site - "Altitude" should be "density altitude," which is really only obvious for folks REALLY familiar with the air density calcs, because Berger's site only asks for Temp and Altitude, which would also require baro pressure and dew point (or percent humidity) if physical altitude were the correct input.
 
You must log in or register to reply here.

Similar threads

D
  • Locked
Applied Ballistics Seminar - Utah - May 6-7th!
Replies
0
Views
355
DocUSMCRetired
D
mcb
Strelok has been removed from both Google and Apples app stores.
Replies
20
Views
5K
ExtremeSquared
E
D
  • Locked
Applied Ballistics - Next Evolution In Technology & KLB + Sig App Updates to AB Connect™
Replies
0
Views
368
DocUSMCRetired
D
D
  • Locked
Kestrel 5700 Applied Ballistics
Replies
17
Views
3K
DocUSMCRetired
D
armoredman
  • Locked
Oddball question - ballistic calculator app?
Replies
10
Views
1K
wally
wally
Back
Top