Burn rate for smokeless propellants - Research results wanted

[Dangermouse]

@Dangermouse Just curious what your ultimate goal is with the data? Wasn't real clear on how you planned to use it, if you don't mind me ask

@Dangermouse Just curious what your ultimate goal is with the data? Wasn't real clear on how you planned to use it, if you don't mind me asking.

Thanks for asking. I would like to know how powders react in changing temperatures so I can decide if testing some other powder is better at long range, given that the temperature at my home range (Red, White, and Blue in Tennille, GA) can vary from the low 20s in Winter to over 100 degrees in Summer.

I shoot a 6BR Norma factory gun with 105 grain Berger hybrid bullets. 29.4 grains of Varget is my load/powder of choice, and Varget has been called temperature stable. Stability to temperature changes, as shown by the empirical evidence uncovered thus far, does not mean unchanging. Evidently it means slow linear change. And muzzle velocity changes for Varget resembles Reloder 15 in the graph above.

If everything else but temperature is held constant, then the increase in muzzle velocity shown in the graph above has to be due to increased chamber pressure. If we take those results at face value, then by reducing ones powder charge at higher temperatures when shooting, one might see smaller groups fall on the target at long range. This translates directly to long range hunting also.

This experiment may also fall inside the capabilities of the equipment--that is, the changes may be too small to detect with a given rifle. M.L. McPherson's book Accurizing the Factory Rifle covers this in great detail.

Merry Christmas to all.

-mouse

 

[Oak_Leaf]

Got it. I kind of figure that's where you were headed. And by the way, I've a good friend that shoots 308 with Varget that will tell you without flinching that Varget is not always temp insensitive. And I'll attest to the fact that RE15 is not always that temp sensitive. Every combo is different.

 

[Dangermouse]

If you have not read the story of shooting tests in the Houston Warehouse, I attach the article. It is a classic in benchrest riflery. Shooting in ideal conditions may not translate directly to winning in the weather, but what you can learn is how one's rifle reacts to different load combinations. This is what we might discover here.

The name of the game is the elimination of variables. By turning every factor contributing to group size variation from a variable into a constant, the process leans toward being deterministic, and away from being random.

The rifle described in the Precision Shooting article was so accurate that the shooter knew where each consecutive shot was going to land, creating a comma shape on the target. Since this happened repeatedly, it was something that could be accommodated for (indoors), to further shrink the group sizes.

Is it possible that a factory Savage Model 12 LRPV could be induced to react similarly? Got to run the experiments to find out.

-mouse

 

[RegionRat]

the process leans toward being deterministic, and away from being random.

Don't jinx yourself... these words may anger the Gods of Enthalpy and Entropy. If aroused, they reach down and screw with you just to keep you in line... LOL

Best Wishes for the next season and Merry Christmas!