Paden
Active Member
Let's use a revolver as an example (or for that matter, a rifle with factory or other load which for whatever reason has jump to the lands, as is the case for most loads aside from the specialty cast/sized for throat niche)... My 45 Colt loads use the 347 grain bullet pictured to the left; they're seated with lots of neck tension and a very strong crimp in the crimp groove. And they are sized to firmly fit my cylinder throats. As verified yesterday, the primer pressure alone is easily adequate to move the bullet against that resistance into the forcing cone. It's evident that it's really not possible to hold a bullet in a case with just neck tension/crimp. Thus the question is... Does the powder ignite before, during, or after the bullet starts moving from the primer pressure; before or after it stops moving from hitting the resistance of the lands; on a micro scale, what does that first millisecond of the pressure curve look like?I think you got it except the powder has to be igniting before the bullet starts moving or you get that stuck bullet pressure rise SEE event.
one more thing that will help get the powder burning better is the bullet engraving the rifling.
this will give a momentary pressure spike you can see on trace equipment so the powder has to be going by then.
I have not seen the primer pop on trace equipment [or I haven't been looking close enough to see it]
but there is always a pressure rise before the little bump [and drop down back to the pressure line] the engraving gives.
In a perfect world, my hope would be that the powder ignites at the same time, if not before the bullet starts moving; once it starts moving it continues to smoothly accelerate, and does not hesitate at the lands... But...(?).
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