Quickload has me stumped

[Sandstorm]

Never ever assume anything... without testing to be sure..
Every firearm is different and every lot of every powder is also going to be different...Test and use caution.

 

[William Vogel]

Thanks, that is the first thing I did, thinking my case capacity was less than the default. But they average .5g more. I only measured 4 cases, and I measured them after firing.

I think you want to use a sized case but I’d really like to know. I’ve documented both fired case volume and sized case volume averages for myself. What is the correct volume to use for the software? I’ve got GRT.

 

[Handley]

I think you want to use a sized case but I’d really like to know. I’ve documented both fired case volume and sized case volume averages for myself. What is the correct volume to use for the software? I’ve got GRT.

Dude I didn't want to even write that because I don't know for sure. I have read that brass is pretty fluid at ignition, that it readily flows to expand to the chamber dimensions. I reasoned that the pressure chamber will be whatever volume the case has at ignition, but I don't know. I'll repost if I can find it, maybe in the QL doc.

 

[Martin52]

I think you want to use a sized case but I’d really like to know. I’ve documented both fired case volume and sized case volume averages for myself. What is the correct volume to use for the software? I’ve got GRT.

See GRT's FAQ page for reasons why a fired case should be used.

Additionally, you might want to trim all cases to the same length before sorting by water volume.

I find placing a light such as a torch behind the case helps consistency in the 'fill' - you want a flat water surface at the top of the case neck, neither concave nor convex.

 

[William Vogel]

See GRT's FAQ page for reasons why a fired case should be used.

Additionally, you might want to trim all cases to the same length before sorting by water volume.

I find a placing a light such as a torch behind the case helps consistency in the 'fill' - you want a flat water surface at the top of the case neck, neither concave nor convex.

Thanks, I’ll read the FAQ. Expanded case volume makes sense and it’ll be better for my predictions. I had adjusted volume to sized and although my volume isn’t far off from what’s there, it’ll lower my pressure prediction and that’s good. I’m not over pressure but close. This should help.

 

[Ned Ludd]

I think you want to use a sized case but I’d really like to know. I’ve documented both fired case volume and sized case volume averages for myself. What is the correct volume to use for the software? I’ve got GRT.

As @Martin52 noted - use fired case volume. This is because it represents the best approximation of the the true "pressure cell" in which the chemical reaction (combustion) takes place (i.e. a case expanded to fit the chamber). One caveat to this is that a fired case has contracted ever so slightly after the bullet exits the bore, which is why we can normally extract it rather easily. Further, the expansion of a previously fired and re-sized case does take a certain amount of energy. However, the cumulative effect of these two caveats are considered to be relatively minimal.