Weight sorted cases ..

Ian

Notorious member
The only way a difference in weight of SAAMI Spec cases could make a difference is case volume. That extra weight has to go somewhere and it goes to the inner volume of the case. A little bit of difference in case volume can make a significant difference in pressure.
I expect that cases of the same volume would perform the same regardless of weight or head stamp.

True, but not the whole story. Rim thickness, bevel, and extractor groove depth are variables which do not affect internal volume.
 

462

California's Central Coast Amid The Insanity
I knew if I waited long enough, Ian would say what's been running round inside my head from the thread's beginning.

Can't recall the rifle's caliber -- one of the millimeters possibly -- but Brand A's brass had rims that were twice as wide (thick) as Brand B's. I didn't weigh them nor measure their volume, but say for discussion that their volumes were identical, it makes sense then that their weights would not have been. Lots of variables within case heads and seems to make weighing cases futile.

I think it comes down to this: we all do the case prep that we think helps improve our guns' accuracy. Whether it actually does or doesn't we may never know. But, if we think it does, it does.
 
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Bret4207

Northern NY Dangerous extremist...???
I don't generally mix brands of cases. I will segregate them by brand. The only place that isn't adhered to is with 38 Spec as I have a few thousand of those. I have seen the rim and extractor groove or other variations between brands that could make up some weight diff. OTOH, if you have two cases with very different rim/extractor shapes and sizes and the cases weigh the same, then the diff has to be internal I'd think.


More variations that add up in the quest of making those mystical "one ragged hole" groups.
 
Weight consistency and brass volume must affect accuracy, otherwise why would Lapua brass that tends to have a consistent weight be so popular among accuracy seeking shooters.
 

Rockydoc

Well-Known Member
True, but not the whole story. Rim thickness, bevel, and extractor groove depth are variables which do not affect internal volume.
You are right, Ian. I hadn’t thought of that. I guess the bottom line is that if one wants to sort brass for accuracy, they should sort by case volume.
 
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RBHarter

West Central AR
The .473 rims , .471-.474 , are an excellent example "oops we ran 100k 45 ACP with 06' grooves" . If memory serves there are at least 3 different shell holders for those clans without adding things like the 284 Win and 6.5 Japanese that may have alternates listed in addition to the standards . I have 6 shell holders and of those 1 fits everything and 3 often have at least a few case that "click-pop" or "turn in" . The other 2 fit what fits and don't fit the rest .
 

Charles Graff

Moderator Emeritus
Over the years, I have delved into case weighting several times. I always stuck to the same lot, of the same make of brass. I won't go into details, but bottom line is it isn't worth the effort. Now start mixing makes and lots and that will be a different story. That said, I don't mix makes of brass and don't mix lots of the same make if I know it.

Addendum: The "placebo effect" isn't just for medications. i.e. handloaders do all sorts of things that only matters inside their own heads.
 
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blackthorn

Active Member
Rockydoc said “The only way a difference in weight of SAAMI Spec cases could make a difference is case volume. That extra weight has to go somewhere and it goes to the inner volume of the case. A little bit of difference in case volume can make a significant difference in pressure.
I expect that cases of the same volume would perform the same regardless of weight or head stamp.”



Ian replied “True, but not the whole story. Rim thickness, bevel, and extractor groove depth are variables which do not affect internal volume. “




I went back and re-read the OP. The OP refers to adding the weight of an anvil. Unless the reference to the anvil was for a generic example only, to me it would fall into the same group as noted by Ian, given the anvil is inserted into the primer pocket as part of the primer and so has no effect on case capacity/volume.​
 

Michael

Active Member
It has interesting watching the discussion.

In reference to the anvil by Blackthorn, I mentioned in the OP just to give point of reference as to just how little 0.5grs of brass is. If we talk about 1gr difference in case weight, just how much is that? What comes to our mind(s)? Without a visual point of reference heaven only knows what we may conjure up. Hence the example of the small pistol primer anvil, it is a little tiny thing. 1 gr difference in case weight compares to taking 2 anvils and pounding them out thin enough, for sake conversation, to wrap round the inside the body of whatever cartridge we are shooting in order to decrease internal capacity by that amount. Go pry out a couple of anvils and ponder just how small they are, and start pounding. How "thick" would that 1 gr peace of rectangular brass be when finished? o_O
 

Petrol & Powder

Well-Known Member
I think Bret hit the nail on the head when he wrote, “it doesn’t matter until it does”.

That may be the most concise piece of wisdom on this topic.

If there ‘s no problem to start with, then measures to correct a non-existent problem will be pointless.

For example, if you turn case necks on a group of casings but the necks were fine to start with; you will expend a lot of effort, but you will see no improvement. I think weighing cases is similar. If you have a group of casings that are relatively uniform to start with, there’s not much to be gained by weighing them.

I can say that on rare occasions I have spent a great deal of effort to precisely load handgun ammunition when seeking the best possibly accuracy. Overall, those efforts on handgun ammunition were a colossal waste of time.

I have also spent a great deal of effort to precisely load rifle cartridges and those efforts occasionally paid better dividends.

Where you start has a big influence on where you finish. If you start with a group of casings all from the same manufacturer, and the same lot – there’s probably not much to be gained by weighing those casings. If you start with all the same brand but from random lots, perhaps weighing them will allow you to cull out some potential problems. Or it may prove to be a waste of time? As Bret stated. “It doesn’t matter until it does”. ;)
 
I've weighed separated and then turned case necks before and the variation in case neck thickness variation varied as much as the weight distribution. I did not separate by volume but plan to do so next. Case neck and case wall thickness probably run down the length of the case. And so, what is the use of turning the case neck except to have an indirect inside concentric inside diameter to create an even neck tension. But instead of turning the neck, an RCBS expander plug can be used expand the resized neck still under the bullet diameter and create a more consistent neck tension against the bullet. I've noticed some bullets I've pulled in the past with swage marks on them from the casing and this is also an issue cast bullet reloaders should consider too.
 

Snakeoil

Active Member
Again, newbie to all this stuff but a decent technical background. If the neck thickness varies, chances are good that when the neck is sized the thinner sections will yield more than the thick section. That would result in a neck that is no longer concentric with the axis of the case. So I can see turning the case necks to assure equal wall thickness to be of value in ultimate accuracy. How much wall thickness contributes to variation in neck tension is difficult to estimate because it has to be proportional to how much thicker one section is and how far around the diameter of the case neck it continues.

Another factor that I think would play a role is material hardness. Are all the cases annealed at the same time? If the neck thickness varies within each neck, does the material anneal equally?

Yesterday, I took my 60 cases, which had all been thru the Lee collet neck sizer and measured the ID using a small hole gauge and a micrometer. What I found was although each case neck had gotten the same trip thru the collet die, the ID varied. When I found one that was bigger than the others, I ran it thru the die again and in some cases it tightened up and others it did not or barely tightened up. My first thought was the hardness or neck thickness varies. I could have carried on and measured each case for neck thickness and also compared OD on each case. But I'm not tolerant of repetitive processes and had to step away from the cases after checking all the IDs. I've decided to shoot all 60 in this coming Sunday's match and then revisit them. I want to see how the IDs compare after being shot. I'm thinking I might skip the neck sizing process if I can maintain a decent neck tension after having been fired. I suspect that the Springfield chamber might not cooperate with achieving that. But my gut is telling me that measuring the cases after having all been fired will tell me more about case consistency when it comes to neck tension. But again, if the hardness varies between cases, the springback should also vary. So, if the OD of the cases varies here and there, depending on if it is bigger or smaller should tell me if the material is harder or softer than others that measure differently.

I have hated winters since I stopped skiing. I'm finding it is more tolerable because it lends itself to basement time for doing things like this. Once the temps are up and the sun is out, my basement time is near zero.
 

RBHarter

West Central AR
Extremely unpopular opinion . I've pilled through ......I wanted to say tomes , but that's not accurate , I'll go with 1,000>< sets of shotgun data . I looked at cases , primers , and wads . I paired single cases , wads , and primers per load and looked for a specific difference that set a load apart by component .

When I started that was about 3 yr before the Federal 209A was dropped and they offered a more in line standard and a magnum only . The 209A in some loads and in several test examples as well as data demonstration would jump pressures 7-10,000 psi . Also at the very beginning of that testing which changed a significant amount of data .

The other contribution was base construction . Paper bases running 3.0 hotter wit Unique when you really look at it makes sense . The nature of it allows displacement of gas . The difference between a formed base in one piece with the case vs a separate base wasn't nearly as dramatic . As I recall like a half gr for equal pressures . The really outstanding difference was the actual shape of the base . Where an otherwise identical load in a FC steel case offered a 13kpsi and WIn and RP offer 12.8 and 12.5 kpsi a Fiocchi was running 9.9 and by the book the same speed . The FC was slightly coned towards the primer the Win and RP were basically flat the Fio has a raised cone above the primer .

Long ago , I want to say Whelen but it may have been Hatcher or another icon at Springfield Armory , there were a series tests done with extended flash tubes to get the fire up to the top/front of the powder column and keep all of the burn in the case vs half the charge entering the barrel . Things like 40 mm , 3"/50 and 5"/38 cased artillery shells are done that way . I suspect that ultimately it acts almost like a duplex load . The big thing was that they found cleaner burns , good news for the auto rifles . They burned slightly less powder for the same results or had gains with reduced pressures . The labor and cost however for use in the 06' didn't trump the gains . It did result ,I suspect , in a change to the shape of the GI case head inside . I haven't ever seen a US GI case older than 1941 , for comparison to a 1905 for example . The more current production has a raised cone above the primer . It seems to come and go in varying degrees .

I mention all of the above because the FC V shaped case bases would promote a full ignition in the base of the powder charge .
The flatter RP and WW tend towards a mushroom swirling effect I think .
The Fio has a full ring of powder below the flash hole and the flash is directed into center of the charge .

I can't say but applying these notions to a brass case with a thicker head expecting the flash tunnel to form a straighter narrower flash higher off the case floor should make for a decimalic improvement in efficiency over say some of the Russo cases that are dead flat .

All theory and conjecture of course as we don't have a window to see what is actually happening .
 
Extremely unpopular opinion . I've pilled through ......I wanted to say tomes , but that's not accurate , I'll go with 1,000>< sets of shotgun data . I looked at cases , primers , and wads . I paired single cases , wads , and primers per load and looked for a specific difference that set a load apart by component .

When I started that was about 3 yr before the Federal 209A was dropped and they offered a more in line standard and a magnum only . The 209A in some loads and in several test examples as well as data demonstration would jump pressures 7-10,000 psi . Also at the very beginning of that testing which changed a significant amount of data .

The other contribution was base construction . Paper bases running 3.0 hotter wit Unique when you really look at it makes sense . The nature of it allows displacement of gas . The difference between a formed base in one piece with the case vs a separate base wasn't nearly as dramatic . As I recall like a half gr for equal pressures . The really outstanding difference was the actual shape of the base . Where an otherwise identical load in a FC steel case offered a 13kpsi and WIn and RP offer 12.8 and 12.5 kpsi a Fiocchi was running 9.9 and by the book the same speed . The FC was slightly coned towards the primer the Win and RP were basically flat the Fio has a raised cone above the primer .

Long ago , I want to say Whelen but it may have been Hatcher or another icon at Springfield Armory , there were a series tests done with extended flash tubes to get the fire up to the top/front of the powder column and keep all of the burn in the case vs half the charge entering the barrel . Things like 40 mm , 3"/50 and 5"/38 cased artillery shells are done that way . I suspect that ultimately it acts almost like a duplex load . The big thing was that they found cleaner burns , good news for the auto rifles . They burned slightly less powder for the same results or had gains with reduced pressures . The labor and cost however for use in the 06' didn't trump the gains . It did result ,I suspect , in a change to the shape of the GI case head inside . I haven't ever seen a US GI case older than 1941 , for comparison to a 1905 for example . The more current production has a raised cone above the primer . It seems to come and go in varying degrees .

I mention all of the above because the FC V shaped case bases would promote a full ignition in the base of the powder charge .
The flatter RP and WW tend towards a mushroom swirling effect I think .
The Fio has a full ring of powder below the flash hole and the flash is directed into center of the charge .

I can't say but applying these notions to a brass case with a thicker head expecting the flash tunnel to form a straighter narrower flash higher off the case floor should make for a decimalic improvement in efficiency over say some of the Russo cases that are dead flat .

All theory and conjecture of course as we don't have a window to see what is actually happening .
You might have a point about turning necks so the bullet is more centered. But, I am shooting my reloads out of a non-benchrest chamber so I think my less-than-perfect rifle will do okay with the reloads I'm feeding it. That said, I think that a FL resize where the case is bumped back just enough so your bold closes snug will help the cartridge seat centered compared to a FL resize where the casing sits in the chamber loser. Atleast, that's what I'm thinking.
 

Snakeoil

Active Member
I never full length resize because I shoot the cases in only one rifle. If the shoulder does migrate forward with these reduced loads, then not resizing should guarantee that the case is indeed centered in the chamber. What it does not guarantee is that the neck is centered in the case.

Now there is a small voice in the back of my alleged brain that doubts some of this neck centering stuff. I watch a friend breech-seat his .25-20SS using a plugged case. I actually made another for him that is adjustable so I know how it works. The bullet is put into the chamber followed by the plugged case and the action closed which breech-seats the bullet into the lands. My first thought was "what assures that the bullet enters the rifling straight?". The answer is nothing, other than the throat of the chamber. But there is clearance so the bullet could be at a slight angle. And that rifle shoots some amazingly tight groups at extended yardages when the shooter does his part. So, that little voice is thinking, if you can just toss a round in and then shove it into the lands with no assurance of it being straight, why does the neck have to be centered?
 

Bret4207

Northern NY Dangerous extremist...???
What makes anyone think every chamber is perfectly centered or aligned to the bore? There's a reason that very accurate rifles usually have someone who built them very carefully. With a production rifle all sorts of weird things happen. Some are peaches, some are lemons.
 

Snakeoil

Active Member
What makes anyone think every chamber is perfectly centered or aligned to the bore? There's a reason that very accurate rifles usually have someone who built them very carefully. With a production rifle all sorts of weird things happen. Some are peaches, some are lemons.
I dunno. Based upon this, I'd think that they are all just about perfect.
 
I never full length resize because I shoot the cases in only one rifle. If the shoulder does migrate forward with these reduced loads, then not resizing should guarantee that the case is indeed centered in the chamber. What it does not guarantee is that the neck is centered in the case.

Now there is a small voice in the back of my alleged brain that doubts some of this neck centering stuff. I watch a friend breech-seat his .25-20SS using a plugged case. I actually made another for him that is adjustable so I know how it works. The bullet is put into the chamber followed by the plugged case and the action closed which breech-seats the bullet into the lands. My first thought was "what assures that the bullet enters the rifling straight?". The answer is nothing, other than the throat of the chamber. But there is clearance so the bullet could be at a slight angle. And that rifle shoots some amazingly tight groups at extended yardages when the shooter does his part. So, that little voice is thinking, if you can just toss a round in and then shove it into the lands with no assurance of it being straight, why does the neck have to be centered?
I never have in the past either but my cases are beginning to stretch enough that some will not chamber. That means FL resizing them.