Brass weight variance.

[ShadeTree]

So recently I loaded up 4 boxes of 7mm-08 for a buddy with a load that's been tested extensively to be good across several of their rifles. After doing so I decided to check the brass weight on fired cases since he recently bought a batch of PPU brass.

I was shocked that the PPU weighed 13 grains heavier than his old blue bag Winchester brass. To me, that was a lot. Did a h20 capacity measurement between the 2 cases and it is only 3/4 of 1 grain difference. Which will equate to about 35 fps. Not near as big of a deal as I thought it would be for that large of a difference between brass. I already did accuracy tests loading that PPU brass and pressure is not an issue as it is a middle of the road charge.

So weighing out brass and culling out brass that is 3-4 grains variance in the same head stamp would seem almost futile for any type of hunting load. Interestingly he has both Remington and Winchester brass fired through the same rifle, and they are only around 1 grain difference on the few I checked. Remington being slightly heavier.

 

[JD338]

Interesting results. Not enough of a difference for most hunters/shooters to even notice the difference.

JD338

 

[Dr. Vette]

So weighing out brass and culling out brass that is 3-4 grains variance in the same head stamp would seem almost futile for any type of hunting load.

It's been show many times that weighing brass really proves nothing and has no usefulness, especially for the same headstamp brass.
As you found, only by checking the actual capacity can you get any useful information.

 

[ShadeTree]

It's been show many times that weighing brass really proves nothing and has no usefulness, especially for the same headstamp brass.
As you found, only by checking the actual capacity can you get any useful information.

I don't weigh brass out, but I would've thought 5-6 grains would be culling status if one were doing so. 13 grains is borderline extreme in my view on a 7mm-08 case which is relatively small.

Yet as long as it isn't overpressure which it isn't, that estimated 35 fps difference is minimal. Heck some loads that shoot well out to 200 or so have that extreme spread or more within brass that weighs virtually the same.

 

[flyingagg]

If you want to cull brass, IMHO, you'd have to do it accroding to H20 capacity

 

[RL338]

As you found, only by checking the actual capacity can you get any useful information.

This
My practice is keeping brass separate by the lot and after 2 firings check the H2O volume. Then I record that number on the box lid.

 

[ShadeTree]

This
My practice is keeping brass separate by the lot and after 2 firings check the H2O volume. Then I record that number on the box lid.

Man, you are way more detailed than I am. Not a bad thing.

My practice on fired rounds is to keep the ones separate that I've killed deer with and put them on a shelf marked "doe" "doe" "buck" etc.

 

[TackDriver284]

I like to buy brass in the same lot, less variables than mixing lots together or sorting cases from lot to lot.

 

[RL338]

Man, you are way more detailed than I am. Not a bad thing.

Number of firings in upper lefthand corner and internal H2O written on bottom of lid.

 

[KinleyWater]

I would have thought that more brass weight equaled thicker brass, which would mean less capacity. While that seems marginally true, it's not nearly so much as I would have imagined. Of course, now that I'm thinking of it, I suppose that could also be because of a slightly longer neck, a slightly thicker rim, etc. Well everyone, thanks for letting me ramble.

 

[Lazy Bushman]

I have never weighed or sorted brass in my life but I rarely shoot to put a hole in a piece of paper. As such I would not have thought that 13 grains between manufactures was all the significant to be honest. I would have assumed that across all the dimension of a case and the variations in copper to zinc ratio's that 13gn's was ok.....but as I said, I have never gone to that much trouble and perhaps I am wrong

 

[slickrem]

So recently I loaded up 4 boxes of 7mm-08 for a buddy with a load that's been tested extensively to be good across several of their rifles. After doing so I decided to check the brass weight on fired cases since he recently bought a batch of PPU brass.

I was shocked that the PPU weighed 13 grains heavier than his old blue bag Winchester brass. To me, that was a lot. Did a h20 capacity measurement between the 2 cases and it is only 3/4 of 1 grain difference. Which will equate to about 35 fps. Not near as big of a deal as I thought it would be for that large of a difference between brass. I already did accuracy tests loading that PPU brass and pressure is not an issue as it is a middle of the road charge.

So weighing out brass and culling out brass that is 3-4 grains variance in the same head stamp would seem almost futile for any type of hunting load. Interestingly he has both Remington and Winchester brass fired through the same rifle, and they are only around 1 grain difference on the few I checked. Remington being slightly heavier.

I found Remington brass weights a little heavier than LC military brass. First time l did l was surprised.

 

[Blkram]

At the end of the day, each person gets to decide to what lengths they will go to fine tune their loading regimen to achieve their desired results...whether it be for hunting or benchrest competition.
I would want to know what the end result is for consistency in accuracy and velocity with a low standard deviation. If I am achieving MOA or better with single digit SD's and am in the velocity range that I am looking for...I am a happy handloader! (And velocity is my last priority here)
And ready for sighting in and practicing at the range, and heading afield for a hunt (as that is my main goal: consistency and confidence that the rifle and ammunition will perform reliably, and when I do my part, put the bullet in the vitals for quick, clean kill.

 

[ShadeTree]

At the end of the day, each person gets to decide to what lengths they will go to fine tune their loading regimen to achieve their desired results...whether it be for hunting or benchrest competition.
I would want to know what the end result is for consistency in accuracy and velocity with a low standard deviation. If I am achieving MOA or better with single digit SD's and am in the velocity range that I am looking for...I am a happy handloader! (And velocity is my last priority here)
And ready for sighting in and practicing at the range, and heading afield for a hunt (as that is my main goal: consistency and confidence that the rifle and ammunition will perform reliably, and when I do my part, put the bullet in the vitals for quick, clean kill.

These were all kept separate and marked as to what they are, I wouldn't want to intermingle them and expect the same POI. Accuracy is fine, but I told the guy to shoot them separate from the Winchester brass I had already had loaded for him from before, as POI may and will likely be some different.

What worried me when I checked the weight was that it would be WAY different. I thought crap, these are gonna be high pressure compared to the others. I had already loaded the 80 rds up as he wanted them all the same. Turns out just .75 grain difference in capacity which should translate to about 35 fps, which is minimal. Shew! Should've took the time to do that before hand. When he gets through them all I'll likely adjust the PPU brass accordingly next go around.

 

[slickrem]

These were all kept separate and marked as to what they are, I wouldn't want to intermingle them and expect the same POI.

I never seen the same POI no matter what I did to brass prep. What I do see now is the right powder, primer, bullet combination, along with .001 neck tension, and group the same without fliers. I believe neck tension and a magnum primer with slower burning powders makes the difference.

According to Boyles law..
If volume increases, then pressure decreases and vice versa, when the temperature is held constant. Therefore, when the volume is halved, the pressure is doubled; and if the volume is doubled, the pressure is halved. For a fixed mass of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional.

Maybe that's why Remington is heavier than the LC brass I have. The Remington case by volume hold 1.5 grains less powder than the LC case.

So I guess if you are gonna cull brass, the lowest internal volume would be best with your loads. And temp insensitive powder would help, Agree ?

In the past I had worse loads with military brass.

I also might add 1.5 grains less is why load manuals tell you to drop down the charge that much if using military brass.

One more thing.... I used two different powders, ball and stick. AA 2460 ball and 4064 stick. One case has more than the other with ball verses stick. So case volume varies with powder selection., water really isn't a good way show volume.