Blown case

[ar15barrels]

Question: Is 92% capacity 92% of what the empty case will hold, or is it 92% of available case space taking bullet seating into account?

Not that I care all that much; my pistol loads are nowhere near full. Just wondering.

If it's quickload derived case fill percentage, it's taking the bullet volume into account so it's the space remaining under the seated bullet.

[divingin]

If it's quickload derived case fill percentage, it's taking the bullet volume into account so it's the space remaining under the seated bullet.

Thanks, Randall.

I think the GRT definition is the same.

I brought it up because "case capacity" by itself is ambiguous.

[Sandspider500]

A 9mm case has .862 cubic centimeters of volume inside, that's from the bottom all the way to the case mouth.

Win 231 is .0931 cubic centimeters per grain.

A 9mm case will hold 9.26 grains of 231, that's all the way to top of the brass, or case mouth. 9.26gr of 231 takes up .862 cubic centimeters. That's 100%. A starting load for a 124gr bullet is 3.8gr in the Lyman 50th. A double charge would be 7.6gr or an 82.2% of a full case. Could you seat a bullet? Yup, but that means you're not paying attention.
IMG_20221005_171011.jpg
From left to right
8gr 231 or 86% full case a double charge
7.6gr of bullseye or 93% full case a double charge
10gr power pistol or 103% full case, a double will not fit without pre compression.
10gr of be-86 it appears 100+% of a full case, a double will not fit without pre compression.

I don't have any sport pistol, but it's the same composition of the bullseye line of flake powders.
IMG_20221005_172312.jpg
All the powder charges with a bullet seated to 1.07, powder compressed. They did seat with more resistance, I could feel the difference.


Flake powders such as unique, blue dot, 800x and 700x take up a lot of space, they're considered fluffy I guess. The powder doesn't lay perfectly flat like a stack of pancakes when metering. Each particle of powder is kinda laying there all jumbled. You can fill a case to the top and seat a bullet no problem. Now if you do that unintentionally you need to take a step back and review your reloading process. Large flake powders also bridge in tubes and funnels. Let's say you want to throw 8gr of 800x, but it only drops 5gr because it has clogged in the tube or funnel, you move to the next case and it dumps 11gr.

So could you double charge a 9mm with common powders? Sure, with some. Can you seat a bullet over double charges? Yes. Again, if you do unintentionally, you really need to rethink how you're reloading. I reload on a single stage press, I charge 50 cases and look into the cases, I can see if something is off. Each case is then handled again as it's put into the shell holder, I can see into the case before the bullet gets set for seating. Guffsters method would work much better, but very time consuming.

A 45 acp case has 1.73 cubic centimeters of volume, a double charge of 231 would fit no problem, no compression needed.

As I was looking through once fired cases to sacrifice, I found a gfl case, not fired by me, but range pickup that has a line just above the case head all the way around the circumference of the case. My potato is not cooperating, I'll try and get a closeup pic.

[Sandspider500]

IMG_20221005_175434.jpg
Best I can do.