7 X 57 with cast
- Thread starter Ben
- Start date
45 2.1
and weight is not one of the items about it that makes a difference.
Let me see if I've got this right, are you saying the weight of the cases doesn't make a difference ?
I'm of the opinion that a 31 gr. difference in Case A and Case B will make a difference down range.
Why do benchrest shooters sort cases by weight ?
The US Military tosses cases that don't meet weight specs for sniper loads.
Ben
and weight is not one of the items about it that makes a difference.
Let me see if I've got this right, are you saying the weight of the cases doesn't make a difference ?
I'm of the opinion that a 31 gr. difference in Case A and Case B will make a difference down range.
Why do benchrest shooters sort cases by weight ?
The US Military tosses cases that don't meet weight specs for sniper loads.
Ben
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I was always under the impression that one didn't use the same loads in military 308 cases as commercial for that exact reason. Heavier brass equals smaller case interior. Can lead to higher pressures.
While I don't worry to the 10th of a grain I do like to avoid 30 gr swings in brass.
I too have a bunch of Hornady brass and have found it seems to fall into a couple weight groupings. The groupings are often 10 or more grains apart.
While I don't worry to the 10th of a grain I do like to avoid 30 gr swings in brass.
I too have a bunch of Hornady brass and have found it seems to fall into a couple weight groupings. The groupings are often 10 or more grains apart.
The 31 gr difference caught my eye.
Such a wide range in weight would make my just let them lay, like Ben said.
So, I went to the reloading bench and found some Frontier brass in both .308 Win. and 30-06 calibers.
I picked 10 cases from each caliber and inspected them internally with a light to be sure they were "clean" inside and did not have any dirt or residual debris, as all are range pick up brass. All of the cases had been polished in a vibrator with corn cob media. If these cases in question have not been cleaned, there is a possible explanation for seeing a wider range of weight that would be expected.
The .308 Win brass weight was about 170 grain on my digital scale (which is accurate to 0.002 grains) and showed the lowest weight was 168.7 gr; the highest weight was 171.2 grains.
The 30-06 brass weight was 185 grain and showed the lowest weight to be 183.1 grains and the highest weight to be about 187.6 grains.
While not exactly comparing apples to apples here, as the calibers were not the 7 x 57 , the brand is the same and might speak to quality control issues.
The variance in weight is seen, but not to the large degree of 31 grains.
This is about the same as I usually see -----a 3-5 % weight range variance.
I do not usually shoot the Frontier cases any more , as I mostly shoot .223 Rem. now and nearly all are Lake City.
They, too, show some small variant in the weight. But so does the few Lapua .223 Rem I have ---
This is not meant to be an explanation, but just an FYI for comparison.
Such a wide range in weight would make my just let them lay, like Ben said.
So, I went to the reloading bench and found some Frontier brass in both .308 Win. and 30-06 calibers.
I picked 10 cases from each caliber and inspected them internally with a light to be sure they were "clean" inside and did not have any dirt or residual debris, as all are range pick up brass. All of the cases had been polished in a vibrator with corn cob media. If these cases in question have not been cleaned, there is a possible explanation for seeing a wider range of weight that would be expected.
The .308 Win brass weight was about 170 grain on my digital scale (which is accurate to 0.002 grains) and showed the lowest weight was 168.7 gr; the highest weight was 171.2 grains.
The 30-06 brass weight was 185 grain and showed the lowest weight to be 183.1 grains and the highest weight to be about 187.6 grains.
While not exactly comparing apples to apples here, as the calibers were not the 7 x 57 , the brand is the same and might speak to quality control issues.
The variance in weight is seen, but not to the large degree of 31 grains.
This is about the same as I usually see -----a 3-5 % weight range variance.
I do not usually shoot the Frontier cases any more , as I mostly shoot .223 Rem. now and nearly all are Lake City.
They, too, show some small variant in the weight. But so does the few Lapua .223 Rem I have ---
This is not meant to be an explanation, but just an FYI for comparison.
Exactly!
And as Brad mentioned, the difference in case weight/volume between commercial and military brass is well known and is cause for concern and starting low & working up. 31 grains difference is a bunch and little doubt different lot numbers of brass. A wise decision to weight segregate the brass.
No one said it was everything but it certainly is something worthy of note.
45 2.1
Active Member
People use a plethora of methods to get where they are, wherever that is. Some make a notable difference and some little to none. If you are at the 1 to 2 MOA range, or above, then a lot of these do little for you. When you get under MOA, the things that don't get discussed much take over. You get under a half MOA and other things really need to be learned because those aren't hardly discussed or done at all by the regular method folks. Copying bench rest methods may not get you very far. Why things work the way they do and for what reason is one of those things that need to be learned. You've heard the statement "the name of the game is the same"........ what part of the "same" is important in that it makes a difference?
Joe7436
Member
I'm working with a company and a team of precision shooters. In talking with one of them that I correspond with much, he talked about another precision shooter who shoots better then him. We got to talking about case weight. I mentioned to him that I know a certain faction of shooters on certain forums that are trying all the benchrest techniques with their cases. I mentioned weighing the cases and he chuckled. He told me this story. He was at the Hornady brass factory working with an engineer. The engineer showed him some cases that were almost totally finished except for the extractor groove and head stamping. The engineer weighed them and they were extremely uniform. Then the engineer said watch this as he weighed some cases that were finished and the weighs weren't very uniform. Did any of you get anything out of that story? What you should have gotten is weighing your cases is useless. Just like 45 2.1 said you should be more concerned with the case volume. Now a story about that friend of my friend that shoots really good. He sorts his cases by volume. By doing this he got his ES's and SD's down to single digit figures, in fact got the SD down to "1". He uses alcohol to measure the volume and made a device to fill the cases precisely and thinks he may market it. Anyways he shrunk his groups remarkably and said that sorting by volume was the most productive of all the case benchrest tricks to shrink groups. Makes a lot of sense to me. Trimming to length=good. De burring flashhole=good. Uniforming primer pockets=good. Uniform case neck thickness=good. Weighting cases=waste of time. A chronograph is a great instrument to have. By watching your ES's and SD's you can learn much about your load and perhaps your cases.
KHornet
Well-Known Member
I think it is obvious that even tho I can find no difference in head stamps, I must have some different runs of brass. I have always weighed military brass, inclusive of match brass, and found considerable differences in weights with the same head stamps. However I have never found with the same head stamps more than 10-12 grain variance which was why I was surprised with 30 grain variance. With Military match 06 & 308 with the same headstamp, I have never found more than 3 grain variance. A good percentage of them nearly exact to within 1/10 of a grain.
Joe7436
Member
Those "more than" and "within" add up to further away from "zero" and zero is the name of the game. It's best to sort cases to "zero" volume variance.
If we size the outside of the case and trim to the same length then the outside of the case is pretty much the same for all cases. That said it makes me wonder how internal volume can be even remotely close if case weight varies by 30 grains. The brass isn't on the outside so it must be inside the case so where, that means internal volume must be different.
I can see where weighing to .3 gr batches makes no sense but refuse to believe that removing the extreme outliers can't do anything but help.
This is an extreme case for certain. My Hornady brass experience is similar. It is the same as mixing head stamps. I get a couple of distinct groups that often vary by over 10 gr.
I can see where weighing to .3 gr batches makes no sense but refuse to believe that removing the extreme outliers can't do anything but help.
This is an extreme case for certain. My Hornady brass experience is similar. It is the same as mixing head stamps. I get a couple of distinct groups that often vary by over 10 gr.
Joe7436
Member
Now you're thinking. There's this guy that shoots some bottle neck cartridge. He devised a method to expand them to a straight cylinder. Through an equally amazing method he mounts them in his lathe and then turns the entire length of the case wall the same thickness much as we turn our case necks. He's anal about the evenness in cartridge case walls. It made a difference in accuracy.
Another thing too if you weigh cases is how much carbon is on those walls? That adds weight, albeit not a lot, but still does. That guy I mentioned about sorting by volume cleans those cases internally.
Most this stuff doesn't produce much if you don't have a super accurate rifle to shoot these cases in. Then we know all the other things that have to be right too. It certalnly won't hurt to do it though.
KHornet
Well-Known Member
Well I got to the range this a.m. with the Frontier cases that weighed in and around 170 gr loaded with 287641(160 gr) the other half with the lee soup can running 127gr. both over 11gr. of Unique (wish I had more of it). Same test at 50 yds as first reported, only this time, 5 shots went into 1.025" with the 160 gr. Lyman. Five with the 127 soup can went into .9", with 4 going into .725. Cases were neck sized with Lee Collet, not trimmed, tumbled for an hour, primed with Win Std LR pr., and all charges were weighed to within 1/10 of a grain. These loads being half or less of the previous loads shop with the mixed weights prove to me at least that weighing cases to within at least 3-5 grains for consistency enhances accuracy. Will repeat testing at 100 yds next time I get the time to do so.
