Primer impulse-bullet movement - hyperlink fixed

[Krazykarl]

Thanks for the link. I look forward to reading it this weekend.

[markm]

Thanks for the link. I look forward to reading it this weekend.

The primer ignition transfers the energy to the rear of the bullet because the powder charge acts like a non-compressible liquid. The mimic the activity with inert powder-like material which isn't exactly like real ball powder, but it recreates the motion.

[Krazykarl]

Im confused. How does the bullet move without pressure?

I assume the shockwave from the HE, but would that not register as pressure against the base?

Figure 1 shows movement from primer, figure 5 does not?

Would the particulant component of the primer blast initiate bullet movement without actual pressure development?

[MegademiC]

Would the particulant component of the primer blast initiate bullet movement without actual pressure development?

I dont know. After thinking about it, i suppose the explosion causes the primer pressure spikes, which throws the powder into the bullet.

I still dont see a position change in figure5, unless its just too small of a movement for the graph.

[308sako]

Most intriguing article encountered in a very long time. Those of us that attempt to visualize what is happening in those micro seconds of initial ignition appreciate that the ARL has taken a scienctific approach to our pondering. My take aways from the parts I am able to comprehend are what Markm has posted...
Thank you Sir for bringing this thought provoking article to our attention.

[markm]

I'd love to see what that testing would show for the load I shoot which is nearly the opposite approach as far as primer/powder.

[308sako]

I'd love to see what that testing would show for the load I shoot which is nearly the opposite approach as far as primer/powder.

Perhaps if these scientists could also define the percentage of affect on the load that the primer alone is responsible for...

I once had the opportunity to question a few of the leading ballisticians at SHOT regarding the energy required to engrave the rifling and the relative affect twist rate made regarding that. Opinions stated were less than 1/2 of 1 percent of the cartridges potential energy. Since we as reloaders on a hobbyist scale cannot control so many factors, we must simply shoot what works.

[markm]

The best 556 powder thread got me wondering about another factor. I wonder what impact an extruded powder would have on the whole test. We've been shooting a bunch of 3031 lately that is the complete opposite of Mil ball powder. I wonder if that powder charge would also act like a non-compressible fluid too.

[Krazykarl]

Finally read the article and I developed the following conclusions:

1. The shock wave is likely proceeding the particles of combustion. The shock wave is the force that is compressing the propellant AND dislodging the bullet from the case.
2. The particles of combustion and the bulk of the flame behave as a focused JET as these elements are funneled through the flash hole.
3. The burn rate of the propellant become heterogeneous as the shock wave is likely distorting the individual kernels of powder. The physical characteristics of the kernels of powder combined with surface treatment is how burn rate is controlled. Therfore, the propellant once it has been crushed has been physically altered before it is ignited by the particles and flame jet.
4. Cases with low load density may experience the bulk of the propellant conversion into gas inside the barrel and not the case.

[AndyLate]

The best 556 powder thread got me wondering about another factor. I wonder what impact an extruded powder would have on the whole test. We've been shooting a bunch of 3031 lately that is the complete opposite of Mil ball powder. I wonder if that powder charge would also act like a non-compressible fluid too.

The only real difference would be a greater amount of compressible air in a case full of extruded powder compared to ball.

Andy