When fired the brass case swells up to seal the chamber. Bottle neck cartridges often grow in length as the pressure pushes the shoulder forward until it contacts the corresponding shoulder in the chamber. As soon as the pressure drops it begins to spring back however it does not typically return to it’s original dimensions. The natural spring back is desirable as it allows for easy extraction of the empty brass shell from the chamber.
In order to reuse a brass case, we need to bring the size back down to where it can grip the bullet, and chamber in the rifle.
Prior to Sizing
Prior to sizing the brass we need to clean it. When you picked up brass from the range it is contaminated with abrasives. These abrasives range from the dirt on the ground, to carbon inside the case. Either way we do not want to introduce these abrasives to our precision machined sizing die.
There are various products on the market that clean brass. I’ve used most of the them, and even own some of them.
The cheapest way to clean brass is with soap and water. Believe it or not, it works really well, as long as you have some way to dry the brass afterwards. Avoid cleaners that have ammonia in them as they will leach out some of the copper from the brass alloy. Take the brass and put it in a bowl, fill it with hot water, your soap of choice, and then agitate. The cartridges will scrub against each other, accompanied by the soap, the dirt will drop off.
I like to rinse the cases in clean hot water after the first scrubbing. The hotter the water the better, as the hot water will accelerate evaporation and drying of the case. That’s the issue with this method, or really, any wet method, is finding a way to dry the cases. It’s entirely dependent on the ambient weather as to how well they will dry. In a cold humid environment, they might not dry for days.
You can accelerate the drying by placing the brass in the over on one of your retired cooking pans. The oven temp should not exceed 250 degrees, and you should place it on the top rack away from the element to avoid hot spots. You might also take the brass and place it on a pan, spread out, on the back of your truck on a hot summer day with the sun shinning on it. You’ll be surprised hot warm they get.
If you want to take you brass cleaning to the next level, the IOSSO Brass Cleaning kit is a mildly acidic solution that will clean off the carbon, dirt and most corrosion. When I started reloading this was the first brass cleaning solution I purchased. It works quite well, after the brass is cleaned drain it and then rinse it in hot water. Again the hotter the better as it aids in drying. Even though I’ve moved on to more sophisticated means of brass cleaning I still use this method as a final cleaning for swage bullets as it removes the lanolin and castor oil lube off the bullets well.
Most reloaders either start with or wind up with some sort of abrasive dry tumbler. There are at least two dozen different hobby grade tumblers on the on the market. When you start getting into professional grade tumblers, you expand your options into the hundreds. At the core they all work the same. An abrasive media, such as corn cob, or walnut shells are the abrasive. A weighted shaft creates a vibration that interns causes the media to “roll” in the bowl. This action scrubs and polishes the brass.
There is one say to say about the humble dry tumbler. They make for some really good looking brass without much fuss. The performance of the tumbler and your satisfaction with it is entirely dependent on the tumbling media you use, and how often you change it out.
My personal preference is the Lyman pre-treated media. It works well, and lasts a long time. Of course you can get untreated media and treat it with one of the dozens of media “charging” compounds on the market. It’s hard to get bad media that doesn’t polish, even dirty and worn out media polishes, it just takes longer.
Tumblers have been around a long time and are a well established method for cleaning and polishing brass. The distinction between cleaning and polishing is important. Especially when you get into the Ultrasonic cleaners. They clean, but they do not polish. If you toss tarnished brass into the ultrasonic cleaner, they are not going to come out with a mirror finish.
One last thing about tumblers, if you are like me and like to tumble different caliber brass at once, make sure you do a couple things. Do not put brass that can “Nest” in the tumbler together, as it can be near impossible to seperate the cases. For example, 9mm and 40 S&W shouldn’t be tumbled to together, but 9mm and .223 is fine. You wouldn’t want to tumble 45 ACP with your 223 brass, but 45 and 308 Win is fine. Heaven forbid you tumble 25 ACP with just about anything with a case neck larger then .338. There is a solution for this, lyman makes some fish netting bags that holds the brass. Sort prior to tumbling, place in bag, tied off and away you go.
With that said, ultrasonic cleaners are pretty cool devices. They use high frequency sound to vibrate the parts. The vibration is so intense that the cleaning solution has a hard time keeping up, this creates microscopic vacuum bubbles, called cavitation. Cavitation is when a vacuum bubble is created in a fluid, and since nature abhors a vacuum, it forcibly collapses the bubble. The shock wave “scrubs” the surface of the brass lifting off the dirt and grime.
In order for ultrasonic cleaners to work properly, they require the use of distilled water, and usually all chemical additive. This additive is basically a soap, and it helps break down carbon and other contaminates. It’s also pretty easy to overload an ultrasonic cleaner, you can put more brass then it can clean.
An interesting life lesson was learned with an ultrasonic cleaner that is worth sharing. The brass cleaning solution is somewhat acidic and will remove bluing from gun parts. So if you are going to clean both brass and guns, make sure you drain the cleaner completely and use the correct additive prior to switching it on.
While an ultrasonic clean will remove carbon and dirt from brass, it is not a polisher, and it will not polish the brass. More then once I have run batches of brass through my cleaner and come up with a dull finish on the brass. People who like making “Instagram” quality reloads may be underwhelmed by the results, especially considering the cost of these units.
The last method of cleaning has gain popularity in recent years. This is wet tumbling brass in a stainless steel media. I have seen the media take various forms, pins, “chops”, ball bearings, and obloid. How effective the media gets into the nooks and crannies of the brass is determined by the shape of the media.
This method for cleaning brass has high upfront costs, as the tumbler and media can run in excess of $150. Then some method for drying the brass is required. However once this upfront costs have been paid there is very little else that needs to be purchased as most people use common house hold dish detergent to help clean the brass.
There is a reason stainless steel tumbling has become almost the preferred means for brass cleaning, and a lot of it has to do with the finish and the ease of use. However it is a bit of an investment, and for those starting on a budget, the high cost is often the main deterrent.
What ever means you use to clean your brass, when you are done, ensure that it is dry, and that it is free of media. Media likes to get stuck in flash holes, and spent primers like to hold in moisture.
Finding the Right Sizing Die
There are lots of different types of sizing dies on the market, and when trying to choose a die, more often then not, you’re on a budget looking to get the most bang for your buck. For the vast majority of reloaders you’re looking for your sizing die to do two things. Set the shoulder back to within SAAMI or CIP spec, and squeeze the neck down to grip the bullet. If you decap during the sizing then obviously you want the die to pop out the spent primer.
Once you understand what’s going on, you will likely stress a little less over what die to buy and begin to see possible ways to have fun with it.
What Happens?
As the case goes up into the die the first thing it make contact is the neck sizing portion of the die. There are a few different designs, but the initial contact are all meant to do the same thing, ensure the case mouth is roundish. I say roundish, because the button has very limited contact with the case mouth during this stage unless the case is dented. For example a .308 button is likely .306 in diameter, while the case neck ID after firing can be as high as .310.
The next point of contact is usually the decapping pin hitting the bottom of the primer, forcing it out of the primer pocket. That is, if you are depriming, and if the case isn’t a Berdan primed case, at which point this is the point you are likely to break the decapping pin. To be fair, this next point of contact may occur at any point as the ram is lifted up into the die with the primer being removed completely during the cam over.
Soon after the neck is rounded the ID of the sizing die makes contact with the OD of the case neck. The inside of the die, forces the case mouth so that the ID of the case is something smaller then the button diameter. This takes a bit of math, as the case mouth is typically .008in to .014in in thickness. Thus if we want the case mouth ID to be around .304in, then the sizing die must be around .328in at the neck. (Most sizing dies have a fix diameter in the neck, but dies have replaceable bushings)
Following the neck sizing operation, the case’s shoulder is set back. This set back occurs during the “Cam Over” portion of the press stroke. The shoulder is set back to somewhere close to SAAMI or CIP minimum dimensions. All other diameters of the case are also squeezed back close to the minimum dimensions for the case.
As the cast is withdrawn it passes over the sizing button again. This time the sizing button enlarges the case neck, if the case neck was sized down to .304, then the .306 button will pull through an size it closer to .306 (there is some spring back so it may be .305 or .3055). The final dimension here, will help determine the fit between the brass and the bullet, this is critical to achieving good neck tension. Obviously this example is for a .308 caliber bullet.
For a straight wall case it is some what simpler of an operation, there is not typically sizing button the way there is for a bottle neck case, rather you insert the case into a the die and it sizes the whole case body down to the proper diameters. Different calibers may have slightly different areas of contact but they all follow a similar process.
To Carbide or Not to Carbide
Carbide is an extremely hard material that is used for it’s resistant to wear. Due to it’s hardness, it can also be very “Slippery” meaning it has a low coeffient of friction when compared to polished steels, including polished tool steels. This attribute can lower the forces needed for things like sizing. In sawge dies, it can help lower the swaging forces needed to shape a bullet.
Due to Carbides hardness it is a difficult material to machine, limited to grinding or methods such as EDM. Solid carbide sizing dies would be prohibitively expensive, and wouldn’t sell very well, however you do see sizing dies with carbide sizing rings, and carbide sizing buttons. Both of which help to lower the friction during sizing.
Frequently I see claims that carbide sizing dies do not need to be lubricated. It is true, you are much less likely to stick in a carbide die, then in a steel die. This is due to the natural lubricity of carbide. However I have not gone so far as to eliminate the use of lubes completely during sizing. A little bit of lube on an already slick surface helps reduce the friction further, (Notably it is far less lube I would use on a steel die set). I believe this reduces how much the brass is worked and may increase the life span of the brass (I would like to study this more, as its a subjective observation rather objective fact).
There are some downsides to carbide, most notably, it is fragile and it will break if shocked. This shock can be something simple as dropping the die, or letting the ram hit the carbide. This can occurred on a turret press if the turret isn’t aligned to the ram. Once the carbide is cracked or chipped it can leave scratches on the brass. Carbide dies also are more expensive, even though the amount of carbide used in the die is limited.
Most people see the elimination of case lube as worth the price of the die as it eliminates a step, especially when using a progressive press. I have taken to placing a dab of imperial sizing wax on my fingers to lightly lube the cases I handle prior to feeding them through the press. People with automatic case feeders, might consider using a dry lube, such as Hornady one shot, to provide a dab of lubrication.
Often times there are coatings applied to the steel in lieu of carbide. Titanium Nitrite is a popular one. This coating is very thin, less then .001 thick, and provides a hard surface that reduces friction between the brass and the steel or carbide substrate.
Setting up A Sizing Die
Setting up a sizing die is pretty simple. Run the ram up, and place a penny on the shell holder. Screw the die down until it touches the penny. Screw down the locking ring until the die is locked in place. The decapping pin should protrude from the bottom of the die by a 1/4 to 1/2 an inch. Remove the penny.
Slowly run up the ram until it stops at it’s highest point of travel. At no point should the ram touch the bottom of the die. It can come close, but it shouldn’t touch. The die is set up. A penny doesn’t need to be used, the die can be run all the way down until you lightly touch the shell holder, and then backed off by 1/4 turn.
When sizing brass it is completely normal to have a part of the case the does not get touched by the sizing die. The area of the case the isn’t sized should not need to be sized. The brass is very thick near the head of the case. This may not be true of pistols that do not fully support the brass case. This can bulge the case near the head, and a sizing die will not correct the bugle.
After “Debulging” the case it still needs to be run through a conventional sizing die prior to loading.
Full Length Verses Neck Sizing
The vast majority of loading I have done has been with full length sizing dies. I have used some neck sizing dies but have moved away from them. Neck sizing is exactly what it sounds like, only part of the case that is sized is the case neck. This allows the case to grip the bullet and minimizes how much of the brass you are working.
Neck sizing can have a few advantages over full length resizing;
- Reduces the amount the case lengthens due to sizing.
- Allows the brass to maintain it’s conformance to the chamber it was fired in.
- Reduces the over all amount the brass is worked, potentially increasing brass life
It comes with one main drawback, brass that is neck sized may not conform to SAAMI or CIP dimensions, thus it may only chamber in the the rifle it was fired in. In some instances it may not even chamber in the rifle it was fired in, especially if it was a semi automatic. This is because the brass can be stretched on ejection.
Neck sizing proponent claim that since the brass is fire formed to the rifles chamber, it is a better fit, and it will more accurately aligned the bullet to the bore. There is some truth to this, however I remain unconvinced that every rifle benefits from this. Especially rifles that already have a fairly tight chamber. Old military rifles such as my Lee Enfield No 4, may benefit from it due to the chamber being a bit looser, but even then I have not done a direct comparison.
As a general rule of thumb, neck sizing is not appropriate for semi automatic firearms, or for instances where the ammunition will be used in more then one firearm.
The Consequences of Sizing
There are two real consequences around sizing brass, neither can really be avoided. As brass is worked, it work hardens. Work hardening is exactly what it sounds like, and it is an important property of the alloy. For example when the head of the cartridge case if formed it is stamped by a bunter. This makes the brass head harder then the rest of the case. It is critical the hardness is retained as it resists further deformation under pressure.
Soft case heads present a safety issue. However we want the case neck to remain soft and springy, every time we fire the case, stretching the case neck and the compressing it back down to size in the sizing die, we work harden the brass. Over time this hardening will lead to case neck cracking. This can be avoided by annealing the case neck, so long as only the case neck is heated and cooled, and the rest of the brass is not annealed. There are several commercial machines and hobbyist methods for annealing case necks.
The second consequence of sizing is the elongation of the brass. Bottle cases naturally lengthen when fired, but the length can be stretched further due to the action, or on ejection. When we size the case back down to SAAMI/CIP dimensions we typically end up lengthening the case neck.
If the case neck gets too long it will begin to jam up against the transition between the chamber and the throat. This transition is often a 45 degree angle, and can act as a crimp, preventing the brass from swelling under pressure to release the bullet into the throat. The result is always increased pressure. Under extreme conditions even a safe load can drastically over pressure due to pressure created in the chamber from brass that is too long.
For this reason it is important to check case length after sizing. Checking it before sizing will allow marginal cases to pass, these cases would certainly fail after sizing. For this reason I prefer not to load rifle rounds on a progressive press, or if I do, I size and trim the cases prior to feeding them on a progressive press. There are presses out there that will accommodate an automatic case trimmer, if you are willing to spend the money.
Case trimming and annealing will be discussed in a separate write up.
Due to their design straight wall cases typically do not elongate like their bottle neck friends. Thus case trimming or check case length are not critical steps. However they do work harden, cracks to form around the case mouth and when this happens it is time to scrap the brass. Straight wall cases, especially pistol calibers last a longtime.
Quality Control
Cleaning and sizing cases are usually the first two steps to reusing brass. This should be a time when you are inspecting brass, some defects become painfully obvious after cleaning. Cracks along the body or the case neck indicate that brass is time to retire. If primer pockets appear loose, or there is a lot of wear around the extractor groove, that qualifies the brass for the scrap bin. Don’t be afraid to scrap brass. Poor quality brass, usually wont cause catastrophic failure in a firearm, but it will degrade performance and can cause damage to the firearm.
Wrapping this Up
Covering both sizing and cleaning off brass in one write up makes for a long write up. However both of these steps are connected as I know people will clean, size, and then tumble the brass again in order to removed the lube on the outside of the case. Cleaning the brass case is also a pretty straight forward task, with the only differences being how the brass is cleaned.
We didn’t go over all the different sizing dies that are available or why you might choose a small based die over a standard die, however I think for most people starting out, or really even more people who do load development, standard dies are pretty much what is used. Specialty dies are used for specialty loads, and are not typical suitable as a one size fits all solution.
While I talked a lot Lee Precision dies, I don’t consider them to be anything but a good die to start with when on a budget, or when you need an inexpensive die in a pinch. RCBS, Redding, and Hornady all make excellent dies and are a better investment over the long term, however their cost can be prohibitive for those just starting out. In principle the LEE die is not any different in it’s operation then any other die on the market, the notable differences in die’s at typically the way the decapping stem is designed and the materials and finished used in the die construction.
In future write ups we will go over trimming the brass, and how that is accomplished. Stay tuned for that, thanks for reading!