Powder measures dispense by volume, a surrogate for weight. We want smokeless WEIGHT to be ww.w grains.
It's time to get the BP Wt vs Volume paragraphs written.
BP is also dispensed by volume.
Some contend that the volume is what is important, not the weight. I think that this means "always use the vv.v volume, don't use ww.w weight". Weight change is ok, keep volume constant.
I've read 2 theories on this.
First, that BP absorbs water out of the air (hygroscopic) and variations in weight per volume are really variations in the amount of water there is in the BP. Yet I don't and don't see others keep any powder container open, or powder our in an open dish/bowl. I dispense BP in a Lyman 55 with the cover on, others out of plastic ketchup bottles into brass measures. If the BP isn't exposed to the air, how do the water get in? (Another ?? Wouldn't BP shoot cleaner if it had all the water it would hold and still burn right? )
Second, that the % of "fines" varies the wt./volume-but this argues for weight counting the most, doesn't it?
I recognize that the precise volume or wt. of BP isn't critical, or so I'm told.
So, does anyone know? Wt. or volume or ???-what matters?
joe b.