Weight Sorting Brass

[SteveBurton]

For you guys that weight sort brass, how minute do you go? +/- 2 grains, 1 grain, tenth of a grain?

 

[C Harrison]

Three bins for differing weights amongst lapua brass usually does the trick with 1 gr difference.

 

[bill123]

I've done it twice. Both times Lapua 308 in .5gr lots. The first time was with 500rds from random lot boxes. I ended up w 7 lots pretty evenly distributed (fewer on the end lots). Second time was 1000rds from a single lot case. Huge difference. 5 lots with all but about 100 cases evenly distributed n the middle 3 lots.

 

[Deleted member 46119]

There is no hard fast rule.

The brass should be fully prepared before so that trimming, chamfer, debur and primer pocket uniforming does not alter the weight after sort.

I always start out sorting by .1, then I group them. I will go for .1 groups for BR if I feel like it. Otherwise I make "lots" of 50 within a range. Could be .3, could be .5, could be 1.

How much brass for that chambering.
Purpose of the rifle.
Purpose of that lot of brass.

Example: if I had 500 or more Wby 270 brass, I would sort them by .1 then take out lots of 50 that were all in the same .1 window. From there I would cull the extremes for sighters, load torturing, barrel break in, seating depth samples and modified cases. From the remaining "mean" where I don't have 50 in a window, count the remainder, divide my 50 and group em up. Label and go.

I keep the tightest lots for the serious shooting, hunt or match. The others are used for practice or whatever.

 

[stomp442]

Case volume is much more important than case weight. You can actually have differing case weights but end up with the same internal volumes. I use the H20 method and sort keeping cases that are .2 grains above or below a mean measurement that you find fairly quickly once you have done a few. This way I have cases that are less than .5 grains difference between each other at any given time. I also end up with 3 piles of brass, two with different case volumes but still very consistent and a small 3rd pile that doesn't fit with any group and that's generally used for foulers or bagged up and sold.

 

[bill123]

Case volume is much more important than case weight. You can actually have differing case weights but end up with the same internal volumes. I use the H20 method and sort keeping cases that are .2 grains above or below a mean measurement that you find fairly quickly once you have done a few. This way I have cases that are less than .5 grains difference between each other at any given time. I also end up with 3 piles of brass, two with different case volumes but still very consistent and a small 3rd pile that doesn't fit with any group and that's generally used for foulers or bagged up and sold.

I had used weight as a short cut because I believed that it was better than nothing. Can you explain the process of H2O sorting?

 

[g0rd0]

first neck size your brass and trim
then seat a bullet on the unprimed cases (be sure that they are all the same oal)
now weigh them empty then fill with water by using a hypo needle though the flash hole (I use a qtip in the primer pocket to wipe out any excess water) weigh again and subtract the difference
EG, a empty 308win with a 150 grn rn is 432grn full it is 481 grn the cc is 49 grn of water

 

[stomp442]

The way I do it is first prep all the brass the same then seat a spent primer to seal the case and weigh empty. Then I use one of those things for sucking snot out of a kids nose filled with water and use as a water dropper to fill the case. I then use a credit card or similar to scrape off the excess and use a paper towel to mop up any droplets on the case body and then weigh it again. Subtract the full weight from the empty weight to get case volumes.

 

[918v]

Case volume is much more important than case weight. You can actually have differing case weights but end up with the same internal volumes. I use the H20 method and sort keeping cases that are .2 grains above or below a mean measurement that you find fairly quickly once you have done a few. This way I have cases that are less than .5 grains difference between each other at any given time. I also end up with 3 piles of brass, two with different case volumes but still very consistent and a small 3rd pile that doesn't fit with any group and that's generally used for foulers or bagged up and sold.

If you end up with different internal volumes with same weight brass from the same make and lot then you erred in your volume test.

I just did two Winchester 308 cases that are 1.5grs apart in weight and they are .7grs apart in water volume.

In the past I have tested numerous FC, LC, and Lapua cases and found if I sorted to .5gr the case volume variance was insignificant. I currently sort my brass into 1gr lots for expediency.

When establishing volume you have to make sure the cases are from the same lot and have the same length. I collect brass and noted noticeable dimensional differences within brass of the same make over the years. Casehead diameters vary, extractor groove diameters vary, neck thickness, etc. A Winchester case from the 80's is not the same as one made today. Neither is FC. Second, you have to make sure you don't have air bubbles in the case. Third, you have to let the water migrate inside the primer pocket. Finally, you have to make sure the shape of the meniscus is identical between cases. That meniscus is worth half a grain of water on a 30 cal neck.

For me, sorting Lapua by weight into 1gr lots cut the ES by 20 FPS. From 40 to 20 is pretty significant.

 

[bill123]

The way I do it is first prep all the brass the same then seat a spent primer to seal the case and weigh empty. Then I use one of those things for sucking snot out of a kids nose filled with water and use as a water dropper to fill the case. I then use a credit card or similar to scrape off the excess and use a paper towel to mop up any droplets on the case body and then weigh it again. Subtract the full weight from the empty weight to get case volumes.

Thanks for the information. For my purposes, it's a bit more work than I want to get into.

 

[Deleted member 46119]

Somebody need to go find these phisics book.

Case volume can only be properly measured on fired cases before resizing.

Case volume is much more important than case weight. You can actually have differing case weights but end up with the same internal volumes. I use the H20 method and sort keeping cases that are .2 grains above or below a mean measurement that you find fairly quickly once you have done a few. This way I have cases that are less than .5 grains difference between each other at any given time. I also end up with 3 piles of brass, two with different case volumes but still very consistent and a small 3rd pile that doesn't fit with any group and that's generally used for foulers or bagged up and sold.

 

[Mikecr]

I agree with stomp442
If you're not measuring volume, your just assuming volume. Pretty much like anything else that isn't actually measured

And I agree with jfseaman
Cases need to be taken to fully stable in dimension to measure volume(fully fireformed).

 

[stomp442]

I think consistency is key. As long as the brass is prepped the same way or fireformed the results are the same. I like the full length size and trim method so I am positive each case is the same as possible.

Using the dropper I have not had any issues with air bubbles and using the credit card to scrape the meniscus even with the case mouth is about as easy as it gets. Either way you do it you end up with a much more consistent reload and better groups in the long run.

 

[Mikecr]

No, fireformed cases are different than new cases, and same holds for FL sized new or FL sized firformed. They're different, they springback differently.
Most productive is fully fireformed -unsized(closest fitting to actual chamber).
Then you could FL size and measure again if you like. You'll probably cull some more with this.