Another brass sorting question

[Cody Richardson]

Just got 300 pieces of lapua blue box 6br brass, all the same lot. I plan on running them through my same prep process as before: trim to uniform length, run through expander mandrel, neck turn(tight neck chamber), inside chamfer and inspect flash holes. However Id like to sort these in to lots of 75 for matches(F-class), so I don't always have 20-25 cases with one less firing on them, I usually being 100 rounds with me to a 60 shot match and always have about 25-30 left over. what would you say is a good weight variance to start with? I've heard groups of .5 grains and anything within 1.0 grain of each other.

 

[Immike]

Hi Cody, I buy enough boxes and number them, then sort the entire lot in .1 gr rows on a table. Then fill the boxes starting at one end. That's as close as you can get them without culling. I clean and work each box seperately so they stay in that box. To keep the firing the same I shoot them in consecutive order so they always stay even firing count. Put a stip of tape across the top of the box to mark your firings.

 

[Webster]

You didn't mention o.d. chamfer. Any tiny burrs will affect how the neck goes thru a bushing or die. I assume you i.d & o.d chamfer after trimming to length and before running an expander inside or sizing.

One thing I don't understand is some people believe that pushing an expander into the neck pushes high spots to the o.d. so they are removed by neck turning. If you have a high spot on the neck i.d. that's 10 thou in diameter and 5 thou high logic would tell you that a 10 x 5 thou high spot wouldn't appear on the o.d. The entire region around the high spot gets pushed outward and you remove brass from an area that's bigger.

 

[jlow]

Hi Cody, I buy enough boxes and number them, then sort the entire lot in .1 gr rows on a table. Then fill the boxes starting at one end. That's as close as you can get them without culling. I clean and work each box seperately so they stay in that box. To keep the firing the same I shoot them in consecutive order so they always stay even firing count. Put a stip of tape across the top of the box to mark your firings.

Exactly - see here for my Lapua .260 Rem case sort

 

[kyreloader]

I guess the question I have to ask is, why do you even sort by case weight?

 

[brxbrad]

Plus 1...Used to go to extremes as well only to find it is next to impossible to get the perfect bullet, perfect cartridge perfect barrel, perfect condition, perfect shot, all at the same time 20 times in a row...times 3 times....ha

 

[calgarycanada]

If brass is from same lot why bother sorting? I believe it has been proven several times by many experts that weight difference may not be an indicator of internal volume difference. If you have excessive time on hand then may as well measure internal water volume.

 

[jlow]

Well it is because the “experts” are wrong. We can believe what others say and go with it, or we can choose to find out by ourselves.

I have proven to myself multiple times from my own test that weight does in fact correlates to volume. Just in case you think I am a newbie to measuring stuff, I have a graduate degree and 30 years of experience doing laboratory work measuring small weights and volumes. But well I certainly won’t bent anyone’s arms to either believe me or to weight sort brass.

 

[Rtheurer]

I would like to see what the Internal Volume of that single 173.0 case is and what any random five of those 171.3 cases are.

Russ T

 

[jlow]

I've posted lots of graphs and data on this very board many times with data and on not just a few cases - Pretty sure people can find it if they do a search.

Every time this has come out, it's been one of those that drags on slug fest for 10 pages.. : So sorry but I am not ready to do this again for the umpteen time.

My attitude nowadays is if you don't believe me, look up the data. If you still don't believe me, that would be OK for me too. My best advice is do it yourself and convince yourself one way or the other.

 

[Mozella]

I'm not arguing about different case weights, but I'm wondering why a quality case, like Lapua, would have significant weight differences and/or significant volume differences.

I don't know much about making cases out of cartridge brass but my understanding is that they're made from a disc which is made into a cup which is then drawn to the basic case shape in an alternating series of drawing and annealing. In the later stages, there is some trimming done and shaping of the neck and shoulder, forming the primer pocket and head stamp, etc. and eventually the head is turned and the flash hole is pierced or drilled.

I would guess that the process is quite mature and is done automatically by highly precise machines without human intervention. It seems to me that in this day of precision manufacturing, one case would be very much like the next, but apparently that isn't true.

Can someone explain why high quality brass would vary to any great degree in weight and/or capacity? Of course, I'm talking about cases from a single lot from one company which are presumably made at the same time on the same machine from identical starting material. Or, I could be completely wrong about that too. Comments?

 

[savagedasher]

I'm not arguing about different case weights, but I'm wondering why a quality case, like Lapua, would have significant weight differences and/or significant volume differences.

I don't know much about making cases out of cartridge brass but my understanding is that they're made from a disc which is made into a cup which is then drawn to the basic case shape in an alternating series of drawing and annealing. In the later stages, there is some trimming done and shaping of the neck and shoulder, forming the primer pocket and head stamp, etc. and eventually the head is turned and the flash hole is pierced or drilled.

I would guess that the process is quite mature and is done automatically by highly precise machines without human intervention. It seems to me that in this day of precision manufacturing, one case would be very much like the next, but apparently that isn't true.

Can someone explain why high quality brass would vary to any great degree in weight and/or capacity? Of course, I'm talking about cases from a single lot from one company which are presumably made at the same time on the same machine from identical starting material. Or, I could be completely wrong about that too. Comments?

Where is the most weight in the brass! The base when they cut the extraction groove not all are the same.