Velocity vs Brass Weight Experiment.

[Mikecr]

there should at least be a weak relationship given that the outer dimension of the case is fixed at the chamber size.

My point is: the case is not fixed to chamber until it's too late to matter. Until then, initially, a case of ANY weight, can be ANY volume less than max.
It's that aspect of this that sets load density. And clearance to chamber then also affects peak pressure.

I couldn't say that potentials could not be flagged -by weight -by brass lot. But I know that condition will not always pass tests, so it would not be prudent to rely on it solely.
Weak relationships, and assumptions, are bad things to act on.
And let's face it, the real reason many here WANT so badly to embrace case weighing as valuable, is because it's a shortcut.. It seems easy.. AGAIN

Now if I had a case show up 60gr departing from the rest, then yeah I could sleep well with tossing that one.
This is why it's important to hold a full barrel life of brass needed from the SAME lot.

 

[DNADave]

My point is: the case is not fixed to chamber until it's too late to matter. Until then, initially, a case of ANY weight, can be ANY volume less than max.
It's that aspect of this that sets load density. And clearance to chamber then also affects peak pressure.

I think we're getting at the same thing but from different perspectives. I do think there is a weak relationship between the two and that it matters less as the average case volume increases. The brass thickness on a .223 is not proportionately thinner than the brass thickness on a .308 in relation to average volume. It's actually the reverse in that as a proportion the .223 brass thickness is proportionately thicker versus the .308 when compared to volume. This would mean that for a .223, the weight would have a stronger relationship with volume than for a .308. Is it enough to matter, I like data so I would want to look at that data. I think doing the same experiment in a .308 would result in looking at minuscule differences that in the grand scheme of things might not matter. Looking at the .223 data would tell us if that might be the case. If you don't see any effect in something like a .223, I doubt you would see an effect in a larger cartridge.

But, as I said, I like data...