Range Report Alliant TEMP swing

[Asm1]

I have always had alliant as my #1 powder RL15 have served me well accuracy is there.I didn't see temp swings like others have reported,I did see a normal swing that Xball and other ballistic programs factored in automatically.
I always ran My loads very stiff this is where I got away with it.
I now shoot loads that are conservative to max,But not Stiff and I get 1MOA swings in Dope vs XBALL in My 223 Boltgun and 308 Gaser.
exball DOES NOT make up the difference so its now a notebook and input the velocity based on temp in NF Xball..I have the Iphone APP ballistic it does the same as XBALL no Manuel input for Velocity vs Temp..

anyone with a better program LMK..

 

[Lindy]

Re: Alliant TEMP swing

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I did see a normal swing that Xball and other ballistic programs factored in automatically.</div></div>

So no one is mislead, I'm running the latest versions of Exbal on the P.C., on a Pocket P.C. running Windows Mobile, and on a Palm Pilot. None of those versions does compensation of muzzle velocity with temperature.

I have programs which do, but Exbal is not one.

It's easy enough to change the muzzle velocity to match the temperature, though, assuming that you actually know how it changes for the load in use.

Field Firing Solutions and Loadbase can both compensate for changes of muzzle velocity with temperature.

http://www.precisionworkbench.com

 

[Asm1]

Re: Alliant TEMP swing

Correct lindy it was correcting dope to a point,Not velocity..I worded that incorrectly..

 

[stenger]

Re: Alliant TEMP swing

i dont think thre is a way for a program to correct for temp sensitive powders. to many variables

 

[Lindy]

Re: Alliant TEMP swing

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">i dont think thre is a way for a program to correct for temp sensitive powders. to many variables.</div></div>

The programs - there are more than one which do that - are not correcting for "temp sensitive powders."

They are correcting for the <span style="font-style: italic">observed</span> difference in muzzle velocity as a function of temperature of a single load in a single rifle. If you shoot a single load in a single rifle over a chronograph when the temperatures are different, and calculate the difference in average muzzle velocity, and then divide that by the difference in temperature, you have dv/dt, the difference in muzzle velocity as a function of temperature.

The program can then use that figure to calculate what the average muzzle velocity should be at a different temperature.

Is that exact? Nope. And the change might not be quite linear through the observed temperature range.

But it's a lot better than pretending that the muzzle velocity does not change with temperature, which it does.

 

[Eaglet]

Re: Alliant TEMP swing

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ASM1</div><div class="ubbcode-body">I have always had alliant as my #1 powder RL15 have served me well accuracy is there.I didn't see temp swings like others have reported,I did see a normal swing that Xball and other ballistic programs factored in automatically.
I always ran My loads very stiff this is where I got away with it.
I now shoot loads that are conservative to max,But not Stiff and I get 1MOA swings in Dope vs XBALL in My 223 Boltgun and 308 Gaser.
exball DOES NOT make up the difference so its now a notebook and input the velocity based on temp in NF Xball..I have the Iphone APP ballistic it does the same as XBALL no Manuel input for Velocity vs Temp..

anyone with a better program LMK.. </div></div>

Please check the link for a good discussion on the way to adjust for MV changes due to Air Temperature.

http://www.longrangehunting.com/articles/ballistics-temperature-velocity-1.php