Range Report Applied Ballistics and powder temperature feature

[Deleted member 10043]

This app allows for a specific fps per degree Fahrenheit. This is a great feature that is almost useless unless you apply a lot of testing and even then it is going to be a best weighted average based on a best guess. For example, I'm current using for N150 in a .308 as .778 fps per degree. And .674 for a 300 H&H using H4831. So, my question is is it that important to be that precise? Could I just round up or down to the nearest .5 fps? Thus, 1 fps and .5 fps. respectively?

 

[OneShotJim]

Ideally you should develop an MV vs. temperature relationship (which may not be linear) for each load by chronographing your MV at several different temperatures for a particular load. (See TRex Reviews video: SNIPER 101 Part 28 - Temperature Corrections - Rex Reviews - YouTube)
Most ballistics calculators handle this using a linear constant as you describe. Obviously, you need more than two points (MV/temp combinations) to tell how nonlinear your powder might be. I'm in the process of doing this for H4350, but need some cool & cold temperatures to get those data points, already have MV's for 62F and 87F. Hopefully I can fill out my temperature/MV curve with some cool weather during the next two weeks.

Since what you are correcting for is average MV (we never know exactly what the MV will be for any single shot), correcting MV for small ambient temp changes (<10F) might be overkill, depending on your target distance and size. But large temperature differences of 20F or more might make a significant difference, especially at long ranges, and more so for small targets.

 

[LastShot300]

Here is a nice article on the subject at hand, moreover it explains why the right way to do this is going non-linear (as aforementioned), since there are many drawbacks to consider, especially at extreme ranges.

Air Temperature Effects On Muzzle Velocity

99.9% of the programs rely on an extremely simple linear increase, which is not the way to go.

Takes time to collect the datapoints (at least 4 are needed), but it's truly amazing to witness how the Fire Solution works under any temperature when done properly.

 

[Deleted member 10043]

Strelok Pro seems to take this concept for it has 5 data sets to enter based on field conditions rather than a linear progression approach. I'm going to assume at risk that the author is using a regression to estimate MV based on powder temperature.

 

[LastShot300]

Strelok Pro seems to take this concept for it has 5 data sets to enter based on field conditions rather than a linear progression approach. I'm going to assume at risk that the author is using a regression to estimate MV based on powder temperature.

Could you please post an image? Asking because I cannot find where the input is, since the iPhone versions shows a simple linear entry. thanks!

 

[Deleted member 10043]

Press on bullet speed f/s in the cartridge section and it will appear. This is Strelok Pro and not Strelok+. Android. I don't have Strelok Pro for iPhone/iPod.

https://lh3.ggpht.com/2FWAVIN3RMimJboirsONtJwgHF7hn4_DcanZ4bCl5KECTsx1e87A4pLW7RTC0Ce_gQ=h900

 

[LastShot300]

Press on bullet speed f/s in the cartridge section and it will appear. This is Strelok Pro and not Strelok+. Android. I don't have Strelok Pro for iPhone/iPod.

https://lh3.ggpht.com/2FWAVIN3RMimJboirsONtJwgHF7hn4_DcanZ4bCl5KECTsx1e87A4pLW7RTC0Ce_gQ=h900

Ok, but according to the posted image, it's a linear factor the one used, not a non-linear one.

 

[Deleted member 10043]

The next screen should look like this...

I keyed in what are linear amounts but you can put in your own field results. From what I understand you need sets of two variables for nonlinear regression.

 

[LastShot300]

The next screen should look like this...

I keyed in what are linear amounts but you can put in your own field results. From what I understand you need sets of two variables for nonlinear regression.

Nice pic, but unfortunately I cannot tell if the program is doing just linear or non-linear, even if the program allows for several pairs to be entered.

At this point, only the programmer can say for sure.

If you check the article's link, ColdBore 1.0 do both from the data series, and tha's the reason for cannot conclude what Strelok Pro is rally doing. But for the first image, and the iPhone shots, I tend to think it's just a linear regression unfortunately.

 

[Deleted member 10043]

From the developer...

Are you using nonlinear regression for powder temperature inputs in Strelok Pro?

It depends from user inputs.
If user inputs 2 pairs velocity-temperature - it will be linear
If user inputs 3 and more velocity-temperature pairs - it will be nonlinear.

Igor Borisov

Maybe explains why the Pro version doesn't have room for all those reticles

 

[LastShot300]

From the developer...

Are you using nonlinear regression for powder temperature inputs in Strelok Pro?

Maybe explains why the Pro version doesn't have room for all those reticles

Doesn't seem much of a technical explanation...hmmm

Maybe you could ask what method the program uses for non-linear. Because what the author says is not much of an explanation, or he is confusing terms, since a linear regression can also take as many pairs as you wish, which in turns yields a much stronger fit, but linear no matter what.

Non-linear is a completely different thing, so if he answers what method the program uses we can rest assured...and alos try to ask about the reticles!

 

[Deleted member 10043]

I doubt he is going to get technical on linear and nonlinear regression in his program. Anyway, those tools are easily available. It's not a stretch for him to apply the same methodology in his programming. I think this is why he went from a % per fps to a manual paired input; i.e. Strelok+ migrating to Stelok Pro.

For those that don't know the difference between linear and nonlinear regression...

Linear regression calc: Regression Tools - Online Linear Regression (simple least squares analysis)

Nonlinear regression calc: Regression Tools - Online Nonlinear Regression (complex sum of squares analysis)