First off is perspective. Let's assume all the difference in case weight is in the volume powder space then based on the density of the brass (131.6 gn/cc) then 1 grain of brass is worth approximately 0.0076 cc of case powder capacity. For a powder like IMR 4064 the Lee VMD is 0.745 cc/gn. That means that the effect of 1 grain of brass is 0.0076/.0745 or about 0.1 grain of powder capacity. In a 308 Winchester that's about 6 fps of velocity at the max. However, the real effect is likely to be less since the most likely location of the difference is in the rim/extractor groove. Since the web thickness between different case manufactures may be different this can also effect the volume/weight balance. What this means is comparing small volume/weight differences only works in same brand/lot number cases that were processed on the same machines.
sorting by empty case weight?
- Thread starter JeffG
- Start date
61 replies to cover a subject that’s been on this website a 100 times. If you are not shooting in serious competition it doesn’t matter. You can get both opinions. Erik Cortina holds many records and he doesn’t sort. If your cold bore shot is more than 1” out side of a group you have a problem besides case volume. There is no relationship of case wt. to volume. The wt. to volume charts have been on this website many times.
How far is your cold bore shot outside a group of the next 5 shots. You don't need to get OCD about this.
What size group do you think you would shoot standing at 100 yards. In PA most shots are under 100 yards. Do you think you can place a shot on a deer in the center of the chest at 80 yards when it's walking slowly.
Yep, it is pretty sad at times but it seems invariably someone comes in with "I'm new …" and has seen/heard/read/partially read on this or other forums about this or that trend (think Satterlee) wants to know something about it. Them add to the confusion there is often someone posting test data from a worthless test that totally confuses everything.
L.Sherm
Silver $$ Contributor
Does everybody just hunt in PA or shoot just 100 yards.
6BRA
Gold $$ Contributor
The Bison volumizer has been out for several years. Temp/Pressure is very important to remain constant to get accurate readings.
Hmmm??? 12.9 SD and an ES of 56 doesn't seem to me to be all that good, though it is over 250 rounds. I would have been interested to see out of 250, take the 20 of the heaviest and 20 of the lightest and see what the difference is.Just saw this... hope it adds even more excitement.
Exactly!
There are some nuggets of gold in this thread, if you’re willing to wade in with an open mind.
CW
Pretty much worthless piece of marketing. Didn't run any regression of velocity versus weight. No formal analysis was performed.Just saw this... hope it adds even more excitement.
L.Sherm
Silver $$ Contributor
If there's one thing I learned 6-8 years ago on here from a few is test everthing thing yourself and come to your own conclusions, well if you dont thats on you.
My point is the biggest variable is the person holding the rifle. You don't fix that reloading ammo in your basement.
L.Sherm
Silver $$ Contributor
Really? If your rifle and ammo is only capable of 1 MOA is the person pulling the trigger gonna turn it into a .5 moa rifle?
My point is leave nothing on the table, if I'm only gonna shoot 100 yards hunting I wouldn't even bother to reload just buy a box of factory ammo and go hunting.
Explain something to me. If each br case has 30 grs. of powder in it and one case is heavier than the other, what causes it to shoot differently?
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LVLAaron
Gold $$ Contributor
Heavier case = less capacity (in theory). It's not an exact 1:1 correlation. But it beats the pants off measuring H20 capacity.
Here's some data.
docs.google.com
Here's some data.
556_Brassh20.xlsx
Wild Bill IV
Gold $$ Contributor
The OP wants to be able to shoot a one shot kill every time and asks whether case weight sorting is needed!!!
I have been doing this for around 50 years!!!
First of all, weight sorting virgin brass is a waste of time!!!!!! But weighing properly FULL fire formed and case prepped cases will aid in precision, long range hunting loads!!
In my load development, FULL fire form the brass with one shot at just below max pressure signs of virgin brass!!! But, before max loading those virgin cases, I prep by carefully filing the base flat to eliminate variability (the humping or catering around the primer pocket caused by the primer pocket punching operation at the factory) of primer pocket uniformity!!! Words from a process engineer where the brass around the primer pocket will either push in or pull out!!! Plus this creates a flatter, squared up and, more even distribution of loading on the bolt face!!! Chamfering both sides of the flash hole will eliminate the burrs on the inside and create better laminar flow of the primer flash causing more consistent powder ignition!!!!!!! Burrs and sharp jagged edges on the inside of the case creates variability in the weight/volume correlation debate!!!
Unlike semiautomatic, casual reloader-hunter, and timed competition shooters, THE COLD BORE SHOOTER/HUNTER will get better accuracy by having minimal bump and slight case compression on bolt drop!!! My FL bushing dies are set at 0.0005" (compressability length of the 70/30 brass or so called NATURAL SPRING BACK AFTER DIE COMPRESSION) less than max chamber length!!! This eliminates addition case stretching, brass flow, and bolt hammer, and aligns the bullet with the bore!!! This is a modification of the old BR practice of NECK SIZE ONLY!!!
BEFORE FL sizing the FULL fire formed brass, for minimal bump, I inside ream (HERE COMES THE ATTACK OF THE OUTSIDE TURN MOB) and trim to COAL at the same time! TWO OPERATIONS DONE AT THE SAME TIME WITH THE FORSTER HAND TRIM LATHE!!! Then, chamfer the mouth!!
NOW, BIN SORT THE CASES BY WEIGHT because the outside of the cases are the same, and almost all variability in neck thickness, case length, burrs, sharp edges, case stretching, and base irregularity have been greatly reduced or eliminated! Load and shoot (cold bore) by bin batches, watching for fliers on the target and velocity variations recorded by the chronograph!!! Use an infrared thermometer or gun to verify a consistent barrel temperature before locking in (chambering) the next round!!!
Now practice at max range lethality just in case that once in a life time trophy appears!!! Above all, use Hunter's Ethics!!! If unsure of the shot, don't pull the trigger!!! DON'T ATTEMPT A LUCKY SHOT ON THESE WONDERFUL CREATURES THAT GOD GAVE US!!! And for God Sake, minimize the suffering of the game animals!!! The faster the animal stops pumping blood, less adrenal gets into the meat which will reduce the taunted taste of the cooked meat!!!!
I had a tuned Rem 700 BDL varmint special in 7-08 that had a 7 shot tight cloverleaf group of 0.384" max spread at 100 yards with 160gr SGK SBT!! That is a max bullet centerline spread of 0.384-0.284=0.100", MOA would be 0.100"/(π/3)=0.095"
My custom 25-06 gets well below 0.2" MOA with 117gr SGK SBT!!!
I have been doing this for around 50 years!!!
First of all, weight sorting virgin brass is a waste of time!!!!!! But weighing properly FULL fire formed and case prepped cases will aid in precision, long range hunting loads!!
In my load development, FULL fire form the brass with one shot at just below max pressure signs of virgin brass!!! But, before max loading those virgin cases, I prep by carefully filing the base flat to eliminate variability (the humping or catering around the primer pocket caused by the primer pocket punching operation at the factory) of primer pocket uniformity!!! Words from a process engineer where the brass around the primer pocket will either push in or pull out!!! Plus this creates a flatter, squared up and, more even distribution of loading on the bolt face!!! Chamfering both sides of the flash hole will eliminate the burrs on the inside and create better laminar flow of the primer flash causing more consistent powder ignition!!!!!!! Burrs and sharp jagged edges on the inside of the case creates variability in the weight/volume correlation debate!!!
Unlike semiautomatic, casual reloader-hunter, and timed competition shooters, THE COLD BORE SHOOTER/HUNTER will get better accuracy by having minimal bump and slight case compression on bolt drop!!! My FL bushing dies are set at 0.0005" (compressability length of the 70/30 brass or so called NATURAL SPRING BACK AFTER DIE COMPRESSION) less than max chamber length!!! This eliminates addition case stretching, brass flow, and bolt hammer, and aligns the bullet with the bore!!! This is a modification of the old BR practice of NECK SIZE ONLY!!!
BEFORE FL sizing the FULL fire formed brass, for minimal bump, I inside ream (HERE COMES THE ATTACK OF THE OUTSIDE TURN MOB) and trim to COAL at the same time! TWO OPERATIONS DONE AT THE SAME TIME WITH THE FORSTER HAND TRIM LATHE!!! Then, chamfer the mouth!!
NOW, BIN SORT THE CASES BY WEIGHT because the outside of the cases are the same, and almost all variability in neck thickness, case length, burrs, sharp edges, case stretching, and base irregularity have been greatly reduced or eliminated! Load and shoot (cold bore) by bin batches, watching for fliers on the target and velocity variations recorded by the chronograph!!! Use an infrared thermometer or gun to verify a consistent barrel temperature before locking in (chambering) the next round!!!
Now practice at max range lethality just in case that once in a life time trophy appears!!! Above all, use Hunter's Ethics!!! If unsure of the shot, don't pull the trigger!!! DON'T ATTEMPT A LUCKY SHOT ON THESE WONDERFUL CREATURES THAT GOD GAVE US!!! And for God Sake, minimize the suffering of the game animals!!! The faster the animal stops pumping blood, less adrenal gets into the meat which will reduce the taunted taste of the cooked meat!!!!
I had a tuned Rem 700 BDL varmint special in 7-08 that had a 7 shot tight cloverleaf group of 0.384" max spread at 100 yards with 160gr SGK SBT!! That is a max bullet centerline spread of 0.384-0.284=0.100", MOA would be 0.100"/(π/3)=0.095"
My custom 25-06 gets well below 0.2" MOA with 117gr SGK SBT!!!
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I’m glad you brought this back to the original question, for myself case weight isn’t related to cold bore accuracy, for myself it’s about have a tune that’s stable and reliable, after load development I clean the rifle and run a few fouler through the barrel to ensure a cold bore kill shot.
You make a good point where getting the cases as uniform as possible from fire forming and case prepping before weight sorting (e.g. case fully fire formed, removing flash hole burr, turn necks, cases trimmed to a consistent OAL, chamfering, etc.). Then you get a better measurement of case weight to volume by taking a lot of noise out of the data. And that's what I've done when compiling my data.
When you mention the "humping or cratering around the primer pocket" from the manufacturing process and that you filing the base flat, I would think that if there's enough of it, the firing forming would take care of that as the base is pressed against the bolt face during firing. . .???
BTW: When deburring the flash holes, I've found the 21st Century tool is the best since it doesn't put any kind of chamfer in the hole like so many tools do and trims away the burr making a nice uniform flat area around the hole. I've often heard it said that it's not necessary for the Lapua brass. Though I've found it to be not much of an issue with my Lapua brass, I have found there are always a number of cases in a batch that I get substantial filings removed. So, I always run that tool in all my Lapua brass to be sure they're all taken care of. It's only a one time operation, so . . . why not.
Wild Bill IV
Gold $$ Contributor
You make a good point where getting the cases as uniform as possible from fire forming and case prepping before weight sorting (e.g. case fully fire formed, removing flash hole burr, turn necks, cases trimmed to a consistent OAL, chamfering, etc.). Then you get a better measurement of case weight to volume by taking a lot of noise out of the data. And that's what I've done when compiling my data.
When you mention the "humping or cratering around the primer pocket" from the manufacturing process and that you filing the base flat, I would think that if there's enough of it, the firing forming would take care of that as the base is pressed against the bolt face during firing. . .???
BTW: When deburring the flash holes, I've found the 21st Century tool is the best since it doesn't put any kind of chamfer in the hole like so many tools do and trims away the burr making a nice uniform flat area around the hole. I've often heard it said that it's not necessary for the Lapua brass. Though I've found it to be not much of an issue with my Lapua brass, I have found there are always a number of cases in a batch that I get substantial filings removed. So, I always run that tool in all my Lapua brass to be sure they're all taken care of. It's only a one time operation, so . . . why not.
I file the bases before running down the primer pocket uniform tool to have consistent primer pocket depth!!! After all, the uniform tool has a depth stop step that contacts the base itself and stops the cutter from going deeper in the pocket!!. Plus, having more surface area, reduces brass movement!! Even the head stamping causes some irregularity that I have notice when filing bases!!! I prefer to start the full fire forming with uniform primer seating and a flat square base for the high pressure forming of the case!!!
On the subject of inside flash hole chamfer tools, I use the Sinclair tool!! Not only does it chamfer, it also slightly enlarges the flash hole itself (uniformity and consistency)!!! ANOTHER VARIABLE THAT AFFECTS THE WEIGHT/VOLUME DEBATE!!! On Lapua brass, it increase the diameter slightly!!! I have some virgin Lapua brass, and I am going to pin gauge before and after to see the variation of the flash holes!! However, other brass manufacturers have higher variability in flash hole diameters!!! I know for a scientific fact (physics fundamentals), that variation in the hole diameters will slightly increase the ES and STDs!!! Plus, I like a slightly larger flash hole because it will increase the force on the primer and will show high pressure signs sooner on approaching peak powder charge!!!! The slightly larger diameter will also allow slightly more FLOW of the primer flash!!! More flow, better powder ignition!!! With the slight increase of flow, more heat is affecting the powder!!! More heat will overcome the phase change energy requirements faster (in this case, the amount of heat needed for the solid powder particles to turn into a gas)!!!!! This in turn, reduces the severity of irregularities in the smoothness of the pressure curve which improves the efficiency!!! The more efficient, the more consistent!!! THE NAME OF THE GAME IS CONSISTENCY WITH ALL COMPONENTS OF THE RELOADING PROCESS!!!!
CAUTION: DO NOT INCREASE THE FLASH HOLE DIAMETER TOO MUCH!!! TOO LARGE A DIAMETER CAN CAUSE PIERCED PRIMERS (RELEASING CORROSIVE GASES THAT WILL ATTACK BOLT COMPONENTS AND CAN BURN EYES, NOSE, AND/OR THROAT), ENLARGE PRIMER POCKETS, DAMAGE TO THE FIREARM, AND/OR HUMAN INJURY OR POSSIBLY DEATH!!!!!!!!! STAY WITHIN SAAMI SPECS!!!!!
In engineering physics, p (pressure) = F (force) ÷ A (unit area).
By multiplying both side of the equality with A, the formula is now:
F = p x A (in this case the area of the flash hole).
Holding pressure as a constants yields the following statement:
As the area increases, the force will increase proportionally!!!
The primer and the primer pocket can only sustain so much FORCE before they are compromised!!!
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