How are brass cases made?
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JeepHammer
Moderator
Brass comes into the plant in coiled sheets.
Thickness varies for the case being made.
A punch press forms a cup in the sheet, then the cup is punched out of the sheet.
That cup is dropped into a forming die in a high pressure pin press, and extreme pressure is applied,
We are talking enough pressure to make the brass 'Plastic', pushing it up the sides of the pin in the die.
All brass starts out as 'Stright Wall'.
The brass gets softened (called annealing) by heating it,
Then the bottle necked cases get the tops formed into the familiar shape,
Stright wall and bottle neck brass gets trimmed and annealed again.
Depends on the company, some form the primer pocket in the pin press when the case sides are being formed, some cut the brass head for the primer pocket.
The last step is punching or drilling the flash hole.
The case necks are usually annealed one last time before the case is loaded or shipped.
The only exception are rimfire cases, they are drawn out to full length while still attached to the brass sheet, then punched off the sheet, pressed to make the familiar 'Rim' for the primer material and trimmed to length for loading.
Thickness varies for the case being made.
A punch press forms a cup in the sheet, then the cup is punched out of the sheet.
That cup is dropped into a forming die in a high pressure pin press, and extreme pressure is applied,
We are talking enough pressure to make the brass 'Plastic', pushing it up the sides of the pin in the die.
All brass starts out as 'Stright Wall'.
The brass gets softened (called annealing) by heating it,
Then the bottle necked cases get the tops formed into the familiar shape,
Stright wall and bottle neck brass gets trimmed and annealed again.
Depends on the company, some form the primer pocket in the pin press when the case sides are being formed, some cut the brass head for the primer pocket.
The last step is punching or drilling the flash hole.
The case necks are usually annealed one last time before the case is loaded or shipped.
The only exception are rimfire cases, they are drawn out to full length while still attached to the brass sheet, then punched off the sheet, pressed to make the familiar 'Rim' for the primer material and trimmed to length for loading.
Don't know about years past, but here's a very good description of the current manufacturing process.
JeepHammer
Moderator
During about the 4th year of 'Obama is coming for your guns' crap,
I started building my own .22LR cases.
These are pictures of a QC strip pulled from a scroll press I built.
The brass sheet is cut to width, fed into the press,
The press punches guide/feed holes in the brass, then the forming process begins...
Then round 'Slugs' are partly cut, but left attached to the brass sheet.
The next step is to warp, then draw out the brass in a pin punch die set...
I built a 'Scroll' press, keeping the brass moving once pressure is applied so the brass doesn't 'Start/Stop/Start' again,
That leaves 'Draw' lines that weaken the brass.
Once the drawing process begins, the pressure must maintain or increase until the brass is fully formed to length...
The next step is to cut the formed brass out of the brass strip, then put the brass in a second press to turn the round bottom into the familiar flat bottom you know with the 'Rim' that holds the primer material...
With a production rate of about 3,200 an hour, I had .22 LR ammo when it was running $50 to $75 a hundred on the 'Gray' market around here.
I started building my own .22LR cases.
These are pictures of a QC strip pulled from a scroll press I built.
The brass sheet is cut to width, fed into the press,
The press punches guide/feed holes in the brass, then the forming process begins...
Then round 'Slugs' are partly cut, but left attached to the brass sheet.
The next step is to warp, then draw out the brass in a pin punch die set...
I built a 'Scroll' press, keeping the brass moving once pressure is applied so the brass doesn't 'Start/Stop/Start' again,
That leaves 'Draw' lines that weaken the brass.
Once the drawing process begins, the pressure must maintain or increase until the brass is fully formed to length...
The next step is to cut the formed brass out of the brass strip, then put the brass in a second press to turn the round bottom into the familiar flat bottom you know with the 'Rim' that holds the primer material...
With a production rate of about 3,200 an hour, I had .22 LR ammo when it was running $50 to $75 a hundred on the 'Gray' market around here.
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deerslayer303
New member
Here is a video that shows the process from the brass being made all the way to a finished round. https://youtu.be/HTPXSKkaCAE
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There are two basic methods. One starts with sheet brass. For larger cases (30-06) there is a good series of images in Hatcher's Notebook going from punching brass discs from the sheet, through forming the cups to the finished cases. The other method starts with a slug cut from brass wire and uses impact extrusion dies to form the head and cups that become cases. That second method is the same principle used to make solid bottom aluminum beverage cans from aluminum slugs.
Mr. Guffey has mentioned visiting a cartridge plant and observing there are enough steps involved in forming some brass that they fully anneal it at more than one stage in the process to allow further forming without damage. The last full annealing has to be done before the head and sides forma are finalized, as that process has to harden the head enough to handle pressure and case extraction. Stress relief (partial annealing) of rifle brass neck and shoulder areas happen last, after forming the shoulder and neck, and the head is carefully not annealed at that stage.
Mr. Guffey has mentioned visiting a cartridge plant and observing there are enough steps involved in forming some brass that they fully anneal it at more than one stage in the process to allow further forming without damage. The last full annealing has to be done before the head and sides forma are finalized, as that process has to harden the head enough to handle pressure and case extraction. Stress relief (partial annealing) of rifle brass neck and shoulder areas happen last, after forming the shoulder and neck, and the head is carefully not annealed at that stage.
JeepHammer
Moderator
FlyFish has a pretty good link, shows the cup most brass, including shotgun brass is punched into a cup the punched out of the sheet.
Like I said, virtually all brass is drawn in a pin press, since it takes about 100,000 pounds or more to make the brass go 'Plastic' so it 'Flows' up and around the pin pushing down on it.
This work hardens the brass, so if you stop, you have to anneal the brass so it will 'Flow' again when the press hits it again...
Usually a dusting of dry lube is used in the pressing functions to turn out a reasonable formed case.
The link shows the extraction groove and the primer pocket are cut/drilled at the same time, and usually the primer flash hole is drilled in the same process.
Some cheaper brass (China) use a die that forms the primer pocket, and often times later punch processes the flash hole is actually punched through the case head, which virtually ruins the case.
Keep in mind that any 'Berdan' primed case was punched instead of drilled, the burrs on the inside tell the story.
I make some of my own center fire brass, one at a time...
I haven't spent the money to build a production machine.
Like I said, virtually all brass is drawn in a pin press, since it takes about 100,000 pounds or more to make the brass go 'Plastic' so it 'Flows' up and around the pin pushing down on it.
This work hardens the brass, so if you stop, you have to anneal the brass so it will 'Flow' again when the press hits it again...
Usually a dusting of dry lube is used in the pressing functions to turn out a reasonable formed case.
The link shows the extraction groove and the primer pocket are cut/drilled at the same time, and usually the primer flash hole is drilled in the same process.
Some cheaper brass (China) use a die that forms the primer pocket, and often times later punch processes the flash hole is actually punched through the case head, which virtually ruins the case.
Keep in mind that any 'Berdan' primed case was punched instead of drilled, the burrs on the inside tell the story.
I make some of my own center fire brass, one at a time...
I haven't spent the money to build a production machine.
FrankenMauser
New member
Some straight-walled or straight-taper handgun cartridges have the case body extruded, rather than drawn.
It's a quicker, cheaper process, but (in my opinion) produces an inferior product.
ATK (Speer, Federal, CCI, Blazer, etc.) sells a lot of 9mm ammo in extruded cases.
And, of course, certain cartridges can operate safely (or be loaded to remain safe) in cases turned from bar stock on a lathe.
It's a quicker, cheaper process, but (in my opinion) produces an inferior product.
ATK (Speer, Federal, CCI, Blazer, etc.) sells a lot of 9mm ammo in extruded cases.
And, of course, certain cartridges can operate safely (or be loaded to remain safe) in cases turned from bar stock on a lathe.
The Alexander patent from 1968 makes an interesting read.
Is it just me or is it impressive jeephammer is making his own casings!!!! I'm surprised no one has adressed this. That is a good thing to know. When we had that Obama scare I was researching how to make all my own components like reusing spent primers, casting my own bullets and making my own powder. Never thought of making cases. You should do a youtube video of how to.
JeepHammer
Moderator
You learn a lot when you do it yourself, what copper/zinc/tin (metals) in the brass for best drawing,
What trace minerals are in the brass is a HUGE deal when you start annealing,
And how easy it is to burn those trace minerals off when you don't anneal correctly.
When you use a torch and see that 'Puff' of smoke before your color change paint changes color... The brass is ruined, that 'Puff' was trace minerals escaping and the case will shine since the zinc was just released from the copper...
Ruined a lot of brass before I figured that one out.
The die making on a gang die (several punches at once) is a challenge.
Darn near lost my mind switching from brass button dies (what the scroll press was origionally used for in 1903) to cranking out brass cases.
Gang dies have to be perfectly aligned & the same depth, no margin for error, since its not an inset type die...
I always enjoy people seeing my head stamps! I get to do anything I want from someone's name to insults ("Aim Stupid!" Is my favorite made for a nephew that wasted ammo a few years back).
I don't 'Cast' bullets, I cut and form lead wire.
Casting would be hugely energy efficient, while a sheer and punch will crank out 2,200 an hour on the machine's lowest setting.
Don't have any idea what the full throttle production rate would be since I don't have multiple wire feeders, I still start each wire by hand.
Brass washing .22 LR bullets is easy, plating would require a bunch of specialized equipment and chemicals, not to mention the EPA nightmare...
About every .22 LR bullet is brass washed anyway, so I'm not missing anything.
It's been a trip!
You will learn to cuss in several launguages...
What trace minerals are in the brass is a HUGE deal when you start annealing,
And how easy it is to burn those trace minerals off when you don't anneal correctly.
When you use a torch and see that 'Puff' of smoke before your color change paint changes color... The brass is ruined, that 'Puff' was trace minerals escaping and the case will shine since the zinc was just released from the copper...
Ruined a lot of brass before I figured that one out.
The die making on a gang die (several punches at once) is a challenge.
Darn near lost my mind switching from brass button dies (what the scroll press was origionally used for in 1903) to cranking out brass cases.
Gang dies have to be perfectly aligned & the same depth, no margin for error, since its not an inset type die...
I always enjoy people seeing my head stamps! I get to do anything I want from someone's name to insults ("Aim Stupid!" Is my favorite made for a nephew that wasted ammo a few years back).
I don't 'Cast' bullets, I cut and form lead wire.
Casting would be hugely energy efficient, while a sheer and punch will crank out 2,200 an hour on the machine's lowest setting.
Don't have any idea what the full throttle production rate would be since I don't have multiple wire feeders, I still start each wire by hand.
Brass washing .22 LR bullets is easy, plating would require a bunch of specialized equipment and chemicals, not to mention the EPA nightmare...
About every .22 LR bullet is brass washed anyway, so I'm not missing anything.
It's been a trip!
You will learn to cuss in several launguages...
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deerslayer303
New member
Jeep, I need some custom cases to go with my No. 4 MK 1 (my first rifle, had it since I was 14) it's name is W.W. (whitetail widow maker) [emoji3] It would be awesome to have some cases with that headstamp.
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JeepHammer
Moderator
I would suggest you find some Winchester Western cases when Winchester runs the 'Cowboy' & 'Vintage' cases every couple years.
All those are head stamped WW, and they make them a lot cheaper than I can turn out center fire cases one at a time...
All those are head stamped WW, and they make them a lot cheaper than I can turn out center fire cases one at a time...
deerslayer303
New member
Cool thank you, I will look into that
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JeepHammer
Moderator
DeerSlayer posted a high production video,
But the narrator didnt get the facts quite right...
That video didnt show the brass rolls being punched into the 'Slugs' (wrong term), the 'Cups' shown in the front end of the video that get drawn/forged into cases.
Calling the sulfuric acid bath 'Cleaning', probably doesn't know what happens when acids/caustics come into contact with brass, especally when an electric charge is applied,
It did show electrical induction annealing, which is the fastest & safest way to properly anneal volume production,
But not much to see when there isn't open flames to look at...
Didnt show if the necks are die punched or roll formed...
Die punching is MUCH faster in production,
But roll forming produces a far superior brass both metallurgical & in terms of being concentric. (Think Lupua)
But the narrator didnt get the facts quite right...
That video didnt show the brass rolls being punched into the 'Slugs' (wrong term), the 'Cups' shown in the front end of the video that get drawn/forged into cases.
Calling the sulfuric acid bath 'Cleaning', probably doesn't know what happens when acids/caustics come into contact with brass, especally when an electric charge is applied,
It did show electrical induction annealing, which is the fastest & safest way to properly anneal volume production,
But not much to see when there isn't open flames to look at...
Didnt show if the necks are die punched or roll formed...
Die punching is MUCH faster in production,
But roll forming produces a far superior brass both metallurgical & in terms of being concentric. (Think Lupua)