Shocking Results!

[heikki02003]

Today I weight sorted some .284 Winchester brass. Needless to say I got a shocking result. I know there has been some discussion as to what brass guys are using in .284 Winchesters; either 'straight' .284Win Win brand or necked-up 6.5x284 Lapua,oh the irony). I've read that Jerry Tierney extensively tested both Win and Lapua brass and found 'Win brass shot as accurately as the Lapua brass'. I know that the Win stuff will need to be annealed.

Here is the breakdown.
Started with 200 brass. Two bags of 50 with the same lot#, and 2 other bags of 50 with the same lot# but different from the first. I guess that was a complicated way of saying two groups of 100 with different lot#'s.

All brass was fully prepped. Flash holes deburred, primer pockets uniformed, full length sized, trimmed, necks turned, necks deburred, and inside of necks polished.

12 brass were immediately culled for random things like crimps and off center flash holes.
188 brass were weight sorted into groups with one grain increments. For example, group '205' weighed anywhere from 205.0gn to 205.9gn.

201gn - 2
202gn - 8
203gn - 21
204gn - 52
205gn - 54
206gn - 23
207gn - 14
208gn - 10
209gn - 4

56.3% of the brass were within 2gn!!!!

Just wanted to pass on my results. I thought someone would find this interesting. Anybody have anything to add? Anybody find similar results? Anybody using annealed Win brass? How do Lapua compare to Win in terms of weight uniformity?

 

[tiny68]

I have seen similar distributions with Win and Rem brass. I end up with 5-10% culls and then break into 1 g spread groups/lots to reload. I use the outer lots with fewer brass for my fowlers.

Once you buy the good stuff, you want like the Win very much. My last box of 500 6BR Lapua brass had +95% of them within 1.5 gr. Culls rate is very low. If I can get Lapua, I will bite the bullet and pay the extra bucks. Same is true of Norma and RWS with my experience.

luck, tiny

 

[Ackman]

Now that all this stuff is uniformed and weight-sorted.....take the lightest one from the 201 group and the heaviest of the 209's, and one from every other weight group. Mark the weight then load and fire. After firing, again make sure they're still all the same length then use an eye dropper and carefully fill each with water. Then re-weigh them. If you feel like spending more time, take 2 from each weight group and choose them .5 gr apart. After they're fireformed to your chamber and outwardly as close to the same as possible, it's interesting to see how internal volume correlates to caseweight. The results may be a surprise.

 

[Ackman]

Also, with a set of calipers measure the diameter of the extractor groove. The heavier ones just may be larger in diameter by a couple thousandths. RANDY

Yes, exactly. Brass volume can be anywhere on the case, including extractor groove and also rim thickness/diameter. And it doesn't take much. Weigh some brass shavings from neckturning and see just how little it takes to weigh 1gr.

 

[johnsopa]

After they're fireformed to your chamber and outwardly as close to the same as possible, it's interesting to see how internal volume correlates to caseweight. The results may be a surprise.

Ackman, are you suggesting that maybe internal volume is more consistent even though pure case weight might be off?

 

[Ackman]

After they're fireformed to your chamber and outwardly as close to the same as possible, it's interesting to see how internal volume correlates to caseweight. The results may be a surprise.

Ackman, are you suggesting that maybe internal volume is more consistent even though pure case weight might be off?

Sort of. Brass weighs a whole lot more than powder and it can be distributed anywhere on the case. Weight sorting new brass is completely pointless but people do it. And even with fully prepped brass what I'm suggesting is that caseweight isn't a reliable indicator of case volume. At least in the tests I ran with .223 brass with 2 different headstamps. A .223 case weighs a bit less than 1/2 of what a 284 case weighs. With those .223's there was no correlation at all between weight and volume and the heaviest actually held more water than the lightest. Also, one headstamp had far more caseweight variation than the other, but considerably less volume variation. So I'm saying that weight sorting may well not accomplish the kind of uniformity that people want it to accomplish.

 

[TonyR]

It's nice to know that I'm not the only one struggling with this. Here is what happened when I weight-sorted 500 new pieces of 6.5X284 Lapua brass from the same lot number:

194.00 0
194.25 1
194.50 5
194.75 28
195.00 80
195.25 74
195.50 35
195.75 3
196.00 4
196.25 0
196.50 1
196.75 1
197.00 1
197.25 0
197.50 7
197.75 26
198.00 75
198.25 102
198.50 36
198.75 17
199.00 2
199.25 2


Statistics guys call this 'bi-modal' because there are two peaks. This pattern held for all five boxes individually which was also a big surprise. Made me glad I bought so many because its not hard to get large sets with close weights for F-Class.
I am doing a lot of testing with the extreme weights. I also found that the water weight does not correlate 100% with the case weight but I also found that the repeatablity of the water weight measurement of the same case was very low. I am still trying to figure out how to handle that because I believe that it is an important variable if for no other reason than two cases that weigh the same don't weigh the same after the neck has been turned. Confirms that the brass is not always distributed the same around the case.

 

[P1ZombieKiller]

but I also found that the repeatablity of the water weight measurement of the same case was very low.

Tony,
I want to make sure I understand this point. Are you saying that in your tests, you weighed the water volume of the same case more than once, and came up with more than 1 figure? How many times did you do this? With your findings, if you did that same test 10 times? Would it be 10 different weights? Is water the best thing to use to measure the case volume with? I would think water would 'BOND' together, thus might not be easy to “cap off”. I have seen water actually above the lip of a cup if the lip is at a certain angle.

 

[TonyR]

You understand completely although I only weighed each of them a couple of times before I started think about other hobbies like stamp collecting. It is very frustrating. I think the problem is the surface tension of the water which enables the bubble you refered to form above the rim of the case. I found it very hard to get the bubble to the same height relative to the rim. I have ordered something that will make smaller drops and I am also planning to test some additives that will reduce the surface tension of the water and make the possible size of the bubble smaller. It will change the density of the water as well but I can correct for that. I hate to do this kind of thing but I think it could be important enough that I want to prove that it is not worthwhile before I give up on it.

 

[Bob3700]

All,

Here is yet another question that you may be able to ask.

After all this brass prep and wt sorting, how does the wt of the case when new compare with the wt of the case after 4-5 firings?

After a case has been fired 10 times, does the internal volume change any?

Things that make you go Humm!

Bob

 

[jadams]

Tonyr & Ackerman:
Interesting comment re: water weight changing in the same case.

Recently in a blog by German Salazar a very accomplished handloader and shooter. As I recall he recommended that you put a few drops of Dawn detergent in your water source to break the water tension. I have never tried it, but it may solve your problem.
John

 

[P1ZombieKiller]

I got a better idea.... When ever my tension gets too high, I just pop a cold one... That's how we roll down here in TEXAS.

 

[TonyR]

Bob. The answer to your question is 'Yes' but it is hard to say how much until reliable measurements can be made. I am necking these up to 284 and blowing out the diameter at the body shoulder junction to the Shehane chambering. These fireforming loads do not result in sharp corners after one firing but the shoulders are sharp after the full loads are fired once. The other shocking result is that the fireforming loads have been as precise as anything I've come up with so far. An extremely successful 1000 yard shooter I know told me that some people deliberately over-bump the shoulder when they resize and either have a belted case or use a hard jam to headspace the round because that little bit of extra 'give' helps their accuracy. Another 'Shocking Result!!'

John. I plan to try alcohol first because, if it doesn't work, I'll want to drink the stuff. Actually, I want to use the alcohol because the densities of various alcohol/water mixture are easily found on the WWW and I want to make sure that the mixture is consistent or I'll be creating a new problem. I'm just glad I'm only going to have to do this once with a new set of cases!

 

[BigJim]

Don't throw any stones this way, but weighing each case is useless!! Each ounce of brass DOES NOT weigh the same. Brass is a combination of various metals and in the mix variations will occur it is then poured into a mold and run through a press again and again and again to flatten it into sheets, these sheets are then stamped into cases. And stamped again and again until it forms what you see as your case.

Geeeeeee in this whole process they get the weight within + or -5 gains of total weight or 0.002 % variance, I would say their QC is working.

Your time would be better spent working on your trigger pull and sighting than weighing cases.

Jim