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Messages - Windsage
Here's a question. I load a fair amount of RL-23. If you look at the sizes of the kernels, they range quite a bit in size. So if I weigh a charge that is mostly on the smaller size versus a charge on the larger size, they both weigh the same but will they have the same combustion profile? I shake the container to help mix these different sizes up since there is some settling that will occur. How does volume measurement address this? Seems I would like to have a load that is consistent in the size of the kernels to get the most consistent combustion profile.
Due to natural vibration, everything in a container will slowly settle the smallest and most dense material to the bottom of the container. I also always shake up the can first. Smokeless powder burns from its surface, so smaller pieces would increase the burn rate. Now that we've talked about this, someone will have to sieve a pound of powder within a tight size range to see what the effect on SD is
Windsage can you reference that article for us? I would like to read it.
It was two parts. They only did 10 rounds in each device, but it's the only straight up comparison I have ever seen.
Sorry if this sounds "stupid"
but how do you load a case by volume?
Not like kernels fit together and have no gaps.
Would think that the repeatability would be hard to achieve.
This is the important issue right here. Darkker is right that modern powder is designed by shape to burn with certain characteristics. This is why you see different cut lengths, or ball size, or cylindrical pellets with holes in them. This is all related to surface burn rate, and relies on the volume and thickness of each particle.
The problems is, volumetric measurement is horribly inaccurate in granular solids. You can get decent measurement of liquids because they conform to the vessel, but with solids, you have to contend with settling and fluidity. With a ball powder, you may find that either method works pretty well as long as you don't either cut pellets or compress them as you fill the volumetric device. With extruded pellets, volumetric is problematic. A few years back some guys did some testing with some of the best volumetric equipment and gravimetric equipment and found that using the best of each they got a SD of 9 with the volumetric and 3-4 with weight. In the end it's all about SD and this is what they found.