Reloading 101: The Cartridge Case

By Glen Zediker published on in General, How To, Reloading

Bear with me! We’ll get started on the process of handloading next time when I talk about setting up a sizing die. But before that, it’s good to keep in mind what we’re dealing with, and that is a cartridge case, and also what happens to it during firing, which is what we’re setting out to remedy when we reuse it.

Brass rifle cartridge cases

Cartridge cases are the general object of our attention in handloading.

Rifle cartridge cases are made of brass, well, the reusable cases are (they can and have been made from steel and aluminum). There are no brass mines; brass is an alloy composed of copper and zinc and sometimes tiny amounts of other metals, like lead. The mix is usually about 70/30 copper to zinc. Different manufacturers use a different mix or blend, and that influences the nature of the material, and more about that shortly.

When a round is fired, here’s what happens.

When the firing pin or striker point contacts the primer, the cartridge is driven forward into the rifle chamber (as far as it is able to go).

When the primer detonates and its flame enters the cartridge-case flash hole to ignite the propellant, gases are produced that begin to expand the case.

line drawing of rifle cartridge

Here’s all the pieces-parts. We’ll be talking about each of these over and over again as we go.

As the propellant is consumed, gas pressure increases, the case head is driven backward against the bolt face, and the case neck and case shoulder are pushed forward as the case neck expands to release the bullet. The case essentially swells up like a balloon to fit the chamber, to the limits of the chamber, and this expansion is in all directions. So the back of the case is pushed into the bolt face and the front area is pushed or blown forward, while, during this, the case body is sealing (essentially sticking to) the chamber walls.

A cartridge case begins to contract just about immediately after it expands. The firing process takes scant milliseconds. Brass is both elastic and plastic. “Elastic” means it will stretch and contract. “Plastic” means it will stretch and stay. The elastic quality makes it expand and seal the chamber and then shrink back enough to be removed or extracted from the chamber. Plastic qualities mean it will also have sustained permanent change.

Well, some of it isn’t really permanent because it can be changed again using tools, but some changes are permanent, whether they are literally smoothed over or not. Some cases tend to be harder—less plastic and less elastic—and that is almost always good, or so I say. It’s easy to see that since brass used in a semi-auto has to deal with at least some premature bolt unlocking, a harder composition is less “sticky” in extraction. Even for a bolt-gun, though, harder alloy tends to be smoother cycling. In a semi-auto, case life is strongly influenced by brass composition, and the harder the longer.

Winchester ammunition boxes

Harder composition is better, in my book. That’s true for semi-auto or bolt-action. Harder cases extract easier. My “go-to” brand of commercial brass tends to be Winchester Western, or WW. It’s made of a fairly hard alloy, and also offers generous capacity (thinner walls). A thicker-walled case might be better for semi-auto use, but so many that offer that attribute are also on the soft side.

Thinking about what happened to the case, what it went through, during firing means we can anticipate the results and effects of dimensional changes. The areas of the chamber that have the greatest dimensional difference between those and the loaded round will have the greatest influence on the dimensions of the spent or fired case. Specifically, the spent case neck will now be too oversized to hold a bullet in place.

The case shoulder will have lengthened (elevated if we’re standing the case on its bottom). The case body will have gotten larger in diameter. The case will also have lengthened overall (more about this in another article). What else? Some case material will have moved forward (brass flows in firing) toward the case neck. This material will have come from the area around the case head. The primer pocket will be larger in diameter.

Each firing, brass gets harder overall. In the areas where it expands the most, it gets even harder as it is “worked” through expanding and then being contracted. The tools we use to restore dimensions, the sizing die for good instance, create the contraction. And as suggested, the wall area near the case head gets thinner and the case neck walls get thicker.

Red plastic Bench Rest Die Set box

Next time… We’ll get started on the process of fixing all those blown out cartridge cases.

All this means quite a bit to the handloader. First, get a clear picture of what’s happened to the spent cartridge case. Essentially, it’s expanded to more closely match the chamber dimensions. Of course, that means different spent-case dimensions from different chambers. Likewise, not all brass cases expand, or stay expanded, in the same way.

Case capacity, by the way, isn’t always as important as it might seem. Greater volume does mean more room for propellant, and expanding gases. With faster to medium propellants, it’s a “trade,” in a way of looking at it. A little less propellant in a little smaller capacity case nets about the same as a little more propellant in a little larger capacity case. Pressure and velocity will be about the same, either way. Now, in larger cartridges, and also often with double-base propellants in any size cartridge, more internal volume will very often mean more velocity at suitable pressure. Point is, don’t worry too much about more or less case capacity in .223 Rem. or .308 Win. I think the alloy composition is more important.

Now we can get started on patching them back up for another use…

This was a specially-adapted excerpt from the forthcoming book,” Top-Grade Ammo,” by author Glen Zediker, owner of Zediker Publishing. Click here to order.

What’s your take on resizing and composition? Share your opinions and experiences in the comment section.

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Comments (17)

  • Mike Reiter

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    Thanks for the article Glen. Good information, I inspect each cartridge after cleaning and then again after de-priming and sizing. Occasionally I find a crack in the mouth / neck area or wear in the head. Good to closely inspect your brass! I reload quite a bit and all my practice and hunting ammo.
    I reload because it is very relaxing. Can’t think about anything else when you are reloading and concentration is a must. I can afford to use only factory ammunition (wife doesn’t know my ammo budget), but I take pride in the product.

    Reply

  • John

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    Reloading 101 = Basic reloading. Really hardness of the brass. At this point, If you’ve never reloaded before. I suggest you buy a reloading manual and read the how to reload section over and over until you have it in your memory bank rock solid. Case, primer, powder and bullet what could be easier, right ? Wrong!!!!!! If you make a mistake. You or someone near you could pay for your mistake. This is serious business. Think about a bolt having the locking lugs ripped off it and the bolt coming back thru your cheek. Buy the book and read how to reload over and over.

    Reply

  • Norris

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    Just started reading these blogs recently, a wealth of info and opinion.Thanks one and all. I started reloading a couple of years ago, mainly for cowboy action shooting, but now getting into rifle calibers. I’m an older coot, but find I learn sometinng new every day.

    Reply

  • John

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    Glock Guy is happy with hitting the broad side of a barn. He has no idea of what precision marksmanship is. He might as well stick to a shotgun with bird shot. He really needs to go to a bench rest shooting completion. Then he can see people take 1/8 inch high x completely off the paper with a 6mm PPC. If my bullets aren’t cutting the same hole or touching at 200 yards, I’m pissed. Because it’s not the gun it’s me. I don’t go as far as a bench rest shooter, of weighing my bullets and cases but I do take my powder charge right to the last grain of powder.

    Reply

  • Powder Burns

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    As long case composition seems to be so critical, wouldn’t it be nice if the author had the forethought to include a list of manufacturer, s grading the hardness of various Brands?

    Reply

  • John

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    They should get to this at some point. Witold Pilecki- If you take a candle and smoke your bullet and seat the bullet so that it touched the rifling, you will get better accuracy. When you close the bolt of your KGB sniper rifle the bullet will be in the center of the bore. You do not want heavy marks on the bullet, just clear the soot from the candle with the rifling. If the bullet has to jump forward to contact the rifling it will not be centered. If you do this start your powder charge a couple grains less and look for pressure signs. You should be able to turn you mosin into a tack driver

    Reply

  • Witold Pilecki

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    I reload 7.62x54r for my Russian Mosin-Nagants. For my 91/30 and M-44, I reload to factory spec and re-size/trim my cases. But for my other 91/30 that I turned into a modern tactical rifle (I call it my KGB Sniper Special), I use fire formed brass that I neck-size only. I keep all my cases separated and marked as to how many times they have been fired, and during prep stage, they are all closely inspected. The bullets for my sniper load are .311″ Sierra Match Kings in front of 45 grains of Hodgdon Varget and a Winchester large rifle primer. I slugged the barrel (that’s why I use .311″ and not .308″) and measured the rifle chamber and use a cartridge O.A.L. of 2.875″ keeping the bullet just off the lands. I load everything on a Lee “C-Frame” press. Right now, I am shooting 3″ groups at 200 yards, and can probably get them tighter with practice holding and breathing. I have had a couple of younger former military guys shoot it and do much better than I, so I know its me. I have 100 rounds ready to go for my next range outing.

    @Glock Guy: If you don’t have a good place to reload, or the money to get started, then I understand your always using factory ammo. My Glock 21 devours my .45ACP 200gr plated flat points without a hiccup, and they punch nice clean holes in paper with no lead fouling worries. I know several guys that would do it in a heartbeat if they had a basement, workshop or garage. I personally used to think reloading was a chore that old, cranky, cheap bastards did just to save money. Boy was I wrong! When I finally put the reloading equipment I had bought several years earlier into use, I discovered that I enjoyed reloading as much as shooting itself. True, when you buy your reloading supplies in bulk, it is cheaper than buying factory ammo. But what a great activity to fill those foul weather times in between trips to the range. Developing and testing recipes to come up with a standard that makes it easy to duplicate I find quite interesting. The combinations of bullets, powders and primers are endless. I have introduced three guys to reloading by giving “private” lessons and allowing them to operate the equipment under my guidance. If you’ve never tried it, I highly recommend it.

    Reply

    • hunterbilll

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      Witold Pilecki, Bill here, not sure what cranky old age group is. I enjoyed this reiteration of why we do what we do, reloading. Conforming spent brass from one chamber of a BOLT action today, and make (the ballistics) of the next projectile that leaves the renewed case neck mouth, perform or outperform it’s optimal peak to which it was designed. I have enjoyed this since 1979, I am 65 years of age and continue to read these rags (good rag) because once in awhile I find something I did not know. Thanks CTD.

      Reply

    • Witold Pilecki

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      @hunterbill:

      Hi Bill,

      I used to think that when i was in my twenties. Now I am in my fifties, so now I am definitely one of the old cranky bastards I used to think of. (lol!) Most people don’t believe me when I tell them I have so much fun reloading.

      Reply

    • hunterbilll

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      Fair enough, I only get cranky if I run out of, and have to wait for, MORE components… you know.

      Reply

  • Casey Charles

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    Good stuff. Can’t wait for the next installment to see if we agree on how to set up dies.

    Reply

  • Glock Guy

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    Never use reloads, not even for target practice Factory ammo only

    Reply

    • Jerry

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      Glock, why would you never reload?
      I have a 1st gen. Glock 17, and have shot well over 20,000 rounds of RELOADED ammunition through it, and it still shoots fine.
      Perhaps you’ve had a bad experience from improperly reloaded ammo?
      Almost all of my pistol (9mm, 45acp, .38/.357) and rifle ammo (.222 Rem, .223/5.56×45, .308, 7.62×39, 6.8spc, and 30.06) is reloaded.
      There is no way that I could afford to shoot the volume of ammunition that I do, without reloading.

      Reply

    • Matt

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      Do you mean YOU never use reloads, or are you saying NEVER use reloads, meaning we shouldn’t? Basic grammar on gun websites is deplorable and makes us look uneducated.

      Reply

    • gypsie

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      I’m with you. When somebody can’t or won’t punctuate it can be difficult to figure out what they’re trying to say, so I just skip it and move on.

      I have been reloading since the early ’90s, and some of my guns have never fired a factory round.

      Reply

    • Jerry

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      Gypsie,
      Whenever I buy a new gun, I always run several boxes of factory ammo through them.
      This helps me to establish a baseline to compare my reloads against.
      But the majority what runs through my firearms is all reloaded.
      Besides, reloading is therapeutic to me, and I believe that I get even more enjoyment from shooting what I created.

      Reply

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