Sorting brass by water volume..HOW?
How does one use water to sort brass? I mean, how does water stay inside the case to be weighed? If you use a primer, then the primer will factor into the weight.
If you use any material to block the flash hole, that too becomes part of the equation.
So, how is it done?
Wolf, Here is how I would do this. You might like to get a PIPET. There are 92 pages of these fancy calibrated eye dropper's in the Fisher Scientific Catalog. They are usually marked in ml, millimeters. Now find the weight of water in ml.
Take your trimmed to correct length case and fill with water. Note the ml it took to fill the case.
Now do the math. ml of water x weight of water will give you a number. If the cases vary the number will vary. Sort by number.
This is so much fun.
clean and full length size and br prep al the brass first....
for just volume, seat an inverted used primer in each case, wiegh the primed case, fill with 77f/25c water(i fill from a slow stream at the faucet).....tap the case to remove air, wipe case clear of excess, establish a close to flat miniscus(sp) .that is the shape of the water on the top of the case mouth...just be consistant. wiegh the water/case. the difference in wieght is vol. at 77f water is aprox 1 cc per gr. sort by tenths...... you will need a good lab type scale for this.....
since a typical loading beam scale is plus or minus .1, just the double wieghing of the case/case with h2o would put you at plus or minus .2....not very good in my opinion.
mike in co
Originally Posted by Wolfdawg6422
Last edited by mike in co; 09-29-2011 at 02:57 PM.
doesn't the water drip out the bottom ??
mike in co
Originally Posted by Centerfire
You zero your scale with the empty plugged case. Then you eye drop fill it with water while it sets on the scale.
I put water in a cup next to the scale and add a few drops of alcohol to it to reduce meniscus formation. I use a paper towel corner to bring water level at the mouths.
For plugging of flash holes, I stand the cases(on the scale) on a plastic golf tee inserted into the flash hole.
I don't worry about the little bit of carbon inside fired cases, or to have a higher resolution scale than .1.
Capacity departures from the pack are obvious.
It doesn't make sense to capacity check anything but fully prepped and fully fireformed -unsized cases.
With this, they're as close to the same volume as they're ever going to be.
i use sized...cause its closest to actual firing volume.......different than fired volume( depending on rifle type..br vs all else) and that allows me to do computer based load workup....
the other mike
It does matter a twit what the actual weight of the water is. What matters is that the variance case to case is minimal. Therefore, use fired cases before you remove the primers. Pipette water into them, on the scale. practice on getting the same "bubble" of water above the neck. that is why a pipette. need tight control on water going into the case
Originally Posted by mike in co
unless, as i pointed out one also wants to calculate some potential loads....based on ACTUAL CASE VOLUME...can't do that with just comparisons of case to case.
mike in co
Originally Posted by David Halblom
I hate to say it fellows but that just sounds like to much work for me.........
i don't have enough true br experience to say yes or no, but it is one more variable...and if one can take it to zero...well then it is out of the equation.
i have one set of brass for my 223 br rifle that is all the same wieght and the same volume. use them in matches.
my 1000 yd brass is plus or minus 0.1 gr..but no volume checks.......
mike in co
Has anyone ever emptied and re-weighed cases? In other words weighed them twice? Is water a repeatable medium?
I have my doubts
Has anyone ever seen Mike Ratigan, Glenn Newick, Tony Boyer, Gene Bukys, Lynn Dragoman, David Tubbs, Don Nielson, or Gary O'Cock doing this?
Of course not. You have to do this in the dark and behind closed doors.
yes...the clue is getting them dry and using the same temp water....
tapping the case to release air, filling with a non aireated stream....
mike in co
Originally Posted by alinwa
I am not a benchrest shooter BUT if I was a really serious benchrester I would sort them when shooting them for groups, by the chrono speeds AND where each one grouped. After sorting them in this manner I would see how my next range session went. I bet I would have tighter groups over all.
What I've learned so far
Use fired fully prepped cases.
One way to record results is to place the cases in a loading block. The plastic MTMs work the nuts. Preferably in order by weight. Then using a ruler make 50 blocks on a piece of paper. Record the case weight and then the case weight with primer. Then as you go along write in the filled weights as measured with a good digital scale.
I like to weigh mine at least twice to verify the results. If it comes out more than +/- .04g (and it does maybe 20% of the time) or looks to be way off from the others, Iíll weigh them some more till Iím satisfied with the results.
You can use the flat backside of a knife to get the water at the case mouth level.
Keep a paper towel handy to wipe any water from the outside of the case.
You can fill them fairly accurately from a very slow running tap. Fill and empty them one time before you start capacity weighing to get the inside carbon wet.
If youíre doing cases that have just been fire-formed you may want to FL size. A lot of times it takes a couple firings for all the cases to uniform out. FL sizing to the shortest headspace reading may help to uniform your once fired cases. So itíd probably be better to wait till they have a couple firings on them if you want to do it unsized. Not sure that youíd find much of a difference in what cases get sorted out using the sized or unsized approach.
Keep them in the loading block till youíve finished sorting out. Sort them out into the same place in another loading block. Be suspicious of any case that when empty is in the mid range, but when filled is way off from the filled mid range. Weigh it a couple times again to be sure you didnít make a mistake.