I have yet another theory for getting a lower standard deviation (SD) on muzzle velocity (MV).
A lot of people weight sort cases. I think that’s a waste of time because of inherent varying densities in the brass, especially in the head stamp area. What you really need to do is volume sort cases (which is what case weight sorters think they’re doing).
My method would plug the primer hole, place the empty, unprimmed but otherwise fully prepared case on a scale, tare to zero and fill it with a fluid (TBD but probably paint thinner because it’s less dense than water, has less capillary action than water and would evaporate quickly after being blown out). By taring the plugged case to zero (0), the reading would be the weight of just the liquid, and hence the volume. Filling the case would be much like measuring powder. You could use an eye dropper for the initial squirt, then trickle liquid until it came to the top without spilling over.
And please, no environmental whacko comments about the inherent dangers of using paint thinner. Life is full of risks.
That is an excellent idea. When I was much younger and looking for ways to spend hours at the loading bench, I weight sorted 100 rounds of 22-250 and cut them out into 5 batches. It wasn't a complete waste of time - the results played out just as you would expect - but actual volume would clearly be more accurate. Perhaps you could find a medium less volatile that paint thinner, since fumes might linger and cause higher pressure.
Even through they'd be otherwise ready at the point, I would not finish primer, powder and bullet until I was sure no remnant of liquid or fumes from the fluid remained.Originally Posted by us920669
BTW, I've heard of others measuring by liquid, but in the cases I've read, they actually tried to measure the liquid poured from the case. Again, I think this is folly. How much liquid remant remained in the case after the pour? My method is perfectly accurate as long as 1) the cases are all filled to maximum before the reading is taken and 2) all the liquid and fumes are removed after the measurement is taken.
I think water wouldn't be that bad of a idea. Once your done sorting, shake them dry and hit it with a hair dryer for a couple of minutes. Leave out in the sun for awhile and then a tumbler. Only do it once so the extra work wouldn't be that bad. Most of the time is waiting or doing something else. I do think it would pay dividen's in the end. We lot sort our powders and check bullets for weight and ogive length. First person that does it should weight sort 100-200 and then check volume with fluid. See if weight sorting equals fluid weighting or see if it doesn't. IF it matches then weight sort (easier), but if it doesn't then maybe more thought needs to be put into fluid sorting :-\ :-\ :-\
You are correct about weight sorting. Even in the same lot, regardless of brand, the difference in the case head thickness variance..there is a difference.
If you are looking for better accuracy, in my experience (somewhat limited, somewhat not), believe bullet runout, bullet bearing length, consistent burning powder/primers, case neck thickness, and bullet pull have more of an affect on accuracy.
I'd use water and here's why...
Density is a good thing in this case. With a higher density you will get a measurable difference with a smaller change in volume.
Just a thought, Would there be any advantage to sort your brass by Base to Datum first or do you think it would not make a difference in your readings of case volume?
Later, Brad
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I don't let the cowboys near paint thinner.
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Assuming that he has sized them all already, there should not be a difference in case body length. If he's also fired them once to form them to the chamber, they will all be the same length through the body and stable as well.
Fill the case with ball powder and weigh the powder..The volume differential will determine the sort....Ball powder fills fairly uniform...One or two open charges of ball powder on the bench is much safer than paint thinner...no fumes...less mess...and no drying time....
Just a thought and my two cents (if I sort for volume that is what I would try first)....
I guess I'll be the "whacko" in this case. I understand the reasoning behind the paint thinner is "easier drying" but if you are using an electric scale...............this is just STUPID. Sorry, I don't mean to call YOU stupid, but the technique is flawed. I mean, we are in a reloading room with, in my case, 30,000 primers and 20-45 lbs of GunPowder!!!! People burn down their HOMES deep frying turkeys on Thanksgiving.
;D I'm just saying, sometimes you have to think for others before you give out a great idea. And the idea is GREAT. You have thought something through that has either been overlooked or just not shared yet. In the benchrest and shooting world, "we" are analyzers by nature I think. Always thinking and analyzing this and that, why this and why that, and wouldn't this work better, etc......
I believe the resistance you are going to get from benchresters that are "seasoned" is that if 1/10th of a grain of powder variance doesn't affect their groups at 1000yds, then that sort of precision is a waste of time to them. It is a great idea, with great insight though and I'm sure I'll find myself trying it out and trying to improve upon your idea. I like the water idea, it does make sense that the mored dense medium will give more of a precise measurement with the tolerances that common reloading scales cans measure....
I also like the ball powder idea but see more room for error with that.
AGAIN, Just another opinion, just happens to be mine ;D
I should have never advocated paint thinner evne though I feel safe with it. There are plenty of non-flammable solvents available for this purpose. Some form of liquid is required. Water is unacceptable because of it's capillary action. When water reaches what appears to be the top of the case, you can put 1, 2 and sometimes 3 more drops and the capillary action will retain it without overflow.
L.H. Clark.........you wrote........"I believe the resistance you are going to get from benchresters that are "seasoned" is that if 1/10th of a grain of powder variance doesn't affect their groups at 1000yds, then that sort of precision is a waste of time to them."
Up until about 3 weeks ago I had the same impression, but then I attended The Original Pennsylvania 1000yd Bench Rest Club's 3 day Shooting School. A 1/10gr variance in a powder charge will affect your vertical in a big way at 1000yds. That's why they weigh down to 2/100th's of a grain for their powder charges. Every component in the reloading process is weighed to 2/100th's, even primers.
All your sighters and your record 10 shots will all be assembled from components that weigh exactly the same. Everything is magnified 10x when shooting at 1000yds. Your nice 1/2" group at 100yd is a 5" group at 1000yd. The current WR for 10 shots at 1000yds is 2.815" which translates into .2815" at 100, and we'd all take that.
Damn small cell phone screen!!! >
The last digit in every measurement is an estimate any way. The only way to get an exact measurement in the 100ths place would be to have a measuring device that can measure to the 1000ths place.
Yes 2/100th's is more then 1/100th's, but L.H. Clark said measuring to 1/10th of a grain is good enough and 2/100th's is 5x more accurate/sensitive then reading to 1/10th. And if using your estimate that to get exact you need to go to 1/1000th of a grain, then a scale that reads to 1/10th really is only good to 1 grain and not 1/10th. FYI....one (1) kernel of Varget weighs approx. 2/100th's of a grain.
Scales that read to 1/1000th of a grain are out of my price range. They run from $2000 for the Citizen CX265 to $4,065 for the A&D Phoenix GH252 on the site I was looking at.
At http://www.accurateshooter.com/ in their forums they had a posting showing that case weight means nothing and case capacity is everything.
These photos date me but the Powley Computer asks for the case capacity in grains of water. It doesn't care how much the boiler weighs, it wants to know how big the boiler is to compute boiler pressure and expansion ratio.
[img width=600 height=257]http://i122.photobucket.com/albums/o254/bigedp51/powley-3.jpg[/img]
[img width=324 height=450]http://i122.photobucket.com/albums/o254/bigedp51/casecapacity.jpg[/img]
Well I guess I wasted my money. When I go back for the 2011 World Open, I'll tell the current World Record holder he's all wet.
One of the instructors at the school is the Asst. Editor at AccurateShooter.com
Haven't spent much time in the lab, eh? You can get a measurement with a measuring device that is one order of magnitude more precise than the increments on the scale via estimations. If you have a beam scale graduated in 0.1gn increments you can get a weight to 0.01gn with that scale. The last decimal place would be only and estimate but the tenths place would be spot on.Damn small cell phone screen!!! >
The last digit in every measurement is an estimate any way. The only way to get an exact measurement in the 100ths place would be to have a measuring device that can measure to the 1000ths place.
The inability to do this very thing is one of the shortcomings of a digital measuring tool. You can't tell if a weight is 0.12 or 0.14. It only gives you 0.1.
That said, perhaps the best short range bench shooter ever was happy with powder within 0.1gn (threw them without weighing them, in fact) and he most certainly would not be happy with a lousy 0.285" group @ 100yds. Consistent velocity is what matters at 1000yd, read small standard deviation. With a high BC bullet, a standard deviation of 5 fps would result in right around 3" of vertical spread with 95% certainty. This can be achieved measuring to the 0.1gn since the exact powder charge is really the least important part. Sounds counter-intuitive but it's reality. Not uncommon to see max spreads in the 10fps range which amounts to only about 1.5" vertical spread.
Haven't spent much time in the lab, eh?
That is actually pretty funny! The Chem Lab I worked in had my quote on a huge sign on one of the walls just as you walked in the door. "REMEMBER....The last digit of EVERY measurement is an ESTIMATE".
Yes, actually about 10 years ago I spent alot of time in a lab working with very expensive machines doing mass spec, ect.
You can get a measurement with a measuring device that is one order of magnitude more precise than the increments on the scale via estimations.
Isn't that exactly what I said? The last digit in every measurement is an estimate. It isn't precise though it is an estimate.
If the balance scale in your post is between .1 and .2, you really have no idea if it is .14, .15, .16 ect. You can guess, but you don't know. If your scale weighs to the hundreths then you can guess to the thousanths ect, as you already know, but it is still a guess.
Yes, most short range shooters don't weigh every load they just throw a charge and if you have ever weighed a thrown charge they do deviate, even from a Harrels powder measure.
I guess a lot of different things come into play when your shooting 800-900yds further then a short BR shooter. Sounds like the short range guys could shatter the current 1K World Records if they jumped to 1,000yd shooting.
helotaxi....."The inability to do this very thing is one of the shortcomings of a digital measuring tool. You can't tell if a weight is 0.12 or 0.14. It only gives you 0.1."...... With a scale that reads to 2/100ths of a grain the 100ths would always be an even number, and I agree it could be wanting to read and odd number but we would never know. But if my scale reads .18 I'm surly going to take that as being closer to .2 then to .1 . That .8 which could be a .9 (but we'll never know) is going to give me more verticle at 1K then a .1 which your saying is all the accuracy we can get form a 2/100ths scale.
"If you have a beam scale graduated in 0.1gn increments you can get a weight to 0.01gn with that scale." Maybe I'm not getting something, but how do you get a beam scale that reads to 1/10th of a grain (.1) to read to 1/100th (.01) of a grain? Could you please explain.
Hope this does not sound argumentative, it's not ment to be.
"If you have a beam scale graduated in 0.1gn increments you can get a weight to 0.01gn with that scale." Maybe I'm not getting something, but how do you get a beam scale that reads to 1/10th of a grain to read to 1/100th of a grain? Could you please explain."
You estimate. Which is exactly what I was talking about in my previous post. The needle is some where between say 56.1 and 56.2 gr. You see it is over half way between so you estimate that it is 56.17gr or 56.18gr. You don't get a precise measurement to the last digit.
How much have y'all actually *shot* these loads @ 1k... or are we just arguing theoretically here?
We're on the same page then. When I saw measure to the 0.001 to get accurate at 0.01 I thought you were talking graduated every 0.001 (which would allow you to estimate to the 0.0001 and be on at 0.001).
"How much have y'all actually *shot* these loads @ 1k... or are we just arguing theoretically here?"
My personal range only goes to 878yds, and I have never found a bench in the places I do my shooting, so I guess it would be theoretically on my part.
I should have phrased that as 'at distance'... and unlike some, I don't really care if you shoot from a rest on a bench or a 'pod on the ground. Just seemed like the argument was heading down the path of what 'should' matter vs. what people actually observe on target with their own two eyes...
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