380 acp chrono findings and questions

To learn and introduce new loaders. Tips and tricks from old timers.

Moderators: Chuck, Mustang380gal, Coordinators, Moderators

Sasquatch.45
Posts: 570
Joined: Tue Jan 17, 2006 7:05 pm
Location: Bellevue Ohio

Re: 380 acp chrono findings and questions

Post by Sasquatch.45 »

I don't have any books in front of me right now to give you any examples, but I will try to explain. You might find improvement in your numbers if you use a power with a high volume to weight ratio relative to burning speed. The goal is to fill as much of the case volume as possible. With small charges (volumetrically speaking) there is more room for the power to "slosh" around. For one shot, it might be piled against the primer, giving relatively even ignition, as the primer 'flashes ' through the mass of the powder charge. Another time it might be laying flatter in the cartridge, causing the primers flame front to surface ignite the power, instead of blowing through the charge. The primer blast can start the bullet to travel forward, increasing the case volume while the tepidly burning powder is dragged behind. According to Bergoulli's principle, as the volume increases, pressure drops, and temperature does correspondingly... Further reducing the burning speed of the powder. This effect is further exaggerated by shorter barrels, as it is possible for the slow burning powder to exit the barrel before it is burned. I'm sorry if I'm not doing a very good job of explaining this, I wish I could remember the book that I read so that I could send you to it. Of all things, I believe it was a book for reloading shotgun shells, explaining why they used wads to keep the powder charge tight against the primer flash hole. I once did an extensive study of powder bulk / weight / burning speed for exactly this same .380 quandary. Unfortunately, it's Lost in my attic some place with a whole notebook full of hard won knowledge. It's been a long time, but I'm thinking that one of the more common powders that I picked was Blue-dot. It's a double base powder... Which I personally think are a bit more consistent to begin with... And it's weighed charge filled a bigger volume of the case than the other powders that I was playing with.... But, my brain is half of a century old.... I'm not claiming that it's the answer... But it is a starting point.
No law of prohibition ever prevented a crime of violence, They simply provide a framework for punishment for those who fail to commit suicide after going postal.

The devil never made me do anything…However, he did have a couple of really cool ideals…
Sasquatch.45
Posts: 570
Joined: Tue Jan 17, 2006 7:05 pm
Location: Bellevue Ohio

Re: 380 acp chrono findings and questions

Post by Sasquatch.45 »

as in addendum, I have toyed with the idea of making tiny foam wads too tightly fit in the cartridge... And fill up the extra space... But I have no means of testing the pressure to look for unintended consequences... so it's a little dicey... I never got around to trying it. I AM NOT recommending this... It was just a theory I toyed with. I was wondering if anyone else has ever heard of such a thing though...
No law of prohibition ever prevented a crime of violence, They simply provide a framework for punishment for those who fail to commit suicide after going postal.

The devil never made me do anything…However, he did have a couple of really cool ideals…
User avatar
weakhand luke
Posts: 1493
Joined: Mon Jul 04, 2005 3:46 pm
Location: Sweet Land of Liberty

Re: 380 acp chrono findings and questions

Post by weakhand luke »

Black powder cartridge guys use corn meal over the powder. Bullet compresses everything in the case against the primer. This is rifle cases. I am definately NOT suggesting you try this. In fact, I'm saying out loud, Don't Try This. Another trick is to use floral foam pressed into the case mouth. Floral foam disinegrates into a ball of stink. Again, rifle case. Don't even think about trying this with pistol loading.

There is a reason I like AA9 in 357sig.
Post Reply