VII. Reloading Information

A. Introduction to Handloading

2. Introduction to Reloading Components

by James M. Morrison (jimmm@ibm.net)

Introduction to Reloading Components

There are two major classes of cartridges: rimfire and centerfire. The difference between them refers to the location of the priming compound. Rimfire ammunition has priming compound placed inside the cartridge rim. Centerfire ammunition has a separate component (called a primer) placed in the center of the base of the cartridge.

Since rimfire ammunition does not use a separate primer component, it is not really reloadable by handloaders. Hence, rimfires will be ignored for the remainder of this discussion. Since I don't reload shotgun shells, I'll ignore them, too.

There are four components of a reloadable round of ammunition: bullet, metallic cartridge case, powder, and primer. Once they are assembled, I will refer to them collectively as a "round" of ammunition.

What happens when a round is fired

Each component has a specific job to perform when the round is fired. Let's say a round is placed in a gun, and the gun fired. Whatever mechanisms are employed inside the gun, the gun's firing pin strikes the round's primer. The primer ignites, sending an intense flame through a hole in the base of the metallic cartridge case. The primer's flame is used to ignite the powder contained inside the cartridge case. The burning powder builds up pressure inside the cartridge case, and the bullet is pushed from the end of the cartridge case into the gun's barrel. After a trip down the gun's barrel, the bullet flies through the air and strikes its target.

Now that we have an approximate understanding of what each component does, let's take a more detailed look at each component.

PRIMER

There are two styles of primers available today: Boxer and Berdan. As an American reloader, I seldom see Berdan primed cartridges so I don't feel competent to discuss them. I'm told they're somewhat more difficult to reload.

Boxer primers consist of three separate subcomponents: primer cup, priming compound, and primer anvil. These subcomponents are assembled as purchased, you do not have to assemble the subcomponents yourself. The primer cup is cylindrical, with one end open and the other enclosed. The open end is where the primer anvil is placed, with the priming compound between the two. The primer anvil has an interesting shape, one perhaps best observed (from an already fired primer, for safety) rather than described. The primer anvil's shape is basically a disc with the center raised so it is adjacent to the priming compound. The priming compound is designed to be shock/crush sensitive, and is an explosive mixture. Recently I have seen information stating there is a foil/paper cover between the anvil and priming compound. As I have no intention of taking apart a live primer, I will take this on faith and simply pass along the information. Handle primers with care.

The primer is assembled into the metallic cartridge case so the anvil end (the open end) faces the hole in the metallic cartridge case (called the "flash hole"), and the closed end of the primer cup is somewhat beneath the level of the bottom of the metallic cartridge case. This is so that the primer only ignites when the gun's firing pin strikes it, rather than simply by bluntly striking the base of the cartridge. An example of such blunt impact might be dropping the cartridge on a concrete floor, or when the cartridge is slammed into position by a self-loading gun. Handloaders wishing to keep their current complement of fingers and eyes will carefully check their primer levels.

When the gun's firing pin strikes the primer cup's closed end, it indents the primer cup. When the primer cup is deformed, it crushes the priming compound between the priming cup and the primer's anvil. This ignites the priming compound, which as we said earlier sends a flame through the flash hole in the metallic cartridge case. Once a primer is fired, it is not reused.

Fired primers are a good source of information regarding the pressure of the assembled cartridge. Primers which appear flattened are a good indication of high pressure, and mean you should not increase pressure any further (and possibly even reduce pressure). A knowledgeable, experienced reloader should be consulted for practical advice in this matter.

There are four sizes of primer: small pistol, large pistol, small rifle, and large rifle. Primers also come in standard and magnum strength. Be sure to use the correct type of primer as recommended by your reloading data source. Never switch to another strength (or even change manufacturer) of primer when working with anything besides starting loads. Or put another way, if you are going to change primer vendors or switch to a magnum primer, be sure to work the load up again from the starting load.

Magnum primers are not necessarily required for "magnum" cartridges. Magnum refers (in this case) to the strength of the flame produced by the primer.

Some military loaded ammunition will have primers that are "crimped", meaning the metallic cartridge case has been somewhat reshaped to tightly hold the primer. I believe the crimp is to prevent the primer from backing out under high pressure. Special tools are available for removing crimped in primers.

Some primer manufacturers: CCI, Federal, Remington, and Winchester-Western.

POWDER

There are two kinds of powder: blackpowder, and "smokeless" powder. Blackpowder is actually an explosive, while smokeless powder is a propellant. Blackpowder "blows up", smokeless powder burns fast. Smokeless powder does produce some "smoke", just not nearly as much as blackpowder. Both kinds can be used to reload some cartridges, but as I've never reloaded a metallic cartridge case with blackpowder, I'm going to ignore blackpowder.

Powder is ignited by the primer's flame. There are numerous powders available to the handloader, and selecting the correct one for an individual cartridge and specific application can sometimes be quite a trick. Fortunately, there is an important factor which helps in selecting an appropriate powder: burning rate. Burning rate is roughly how fast a particular powder burns. An added complication is that the burning rate varies based on the pressure inside the cartridge and the barrel. And the pressure changes (rapidly) over time.

Chemically, there are two varieties of smokeless powder: single- and double-based. Single-based powders contain nitrocellulose. Double-based powders contain nitrocellulose and nitroglycerine. The addition of nitroglycerine makes double-based powders burn faster and hotter than single-based powders.

Smokeless powder comes as granules, and the granule shapes describe what category of powder it is. The shapes are: flake, ball (also called spherical), and extruded (also called stick). A particular type of powder will be all one kind of granule shape. The granule shapes as well as the chemical composition of the powder have direct bearing on the burning rate.

It is not possible to discern what kind of powder you have before you just by looking at it. Never mix powders, and unless you are 100% sure what kind of powder you are dealing with, never put it back into a powder cannister. General safety procedures call for having only one kind of powder on the loading bench at a time.

Ideally, a powder will burn cleanly and completely, leaving no residue. When burned, it produces a gas which places pressure against the metallic cartridge case and bullet. The case will slightly expand to more completely fill the gun's chamber, and then the bullet will be propelled down the barrel. We want all of the powder to have burned by the time the bullet leaves the barrel. Muzzle flash is an indication that powder is being burned outside the barrel, meaning you are wasting powder.

There is a basic relationship between how much powder is placed in the case and how much pressure is produced when the cartridge is fired. Special equipment is available to directly measure pressure, but is not strictly necessary to produce safe, accurate reloaded ammunition. Basically, the more powder the higher the pressure the faster the bullet. Too much pressure, though, and accuracy declines. Still more pressure, and you begin to damage components (like loose primer pockets). Throw even higher pressure into the mix and you can damage the gun and/or yourself. The best case scenario in such an instance is embarassment (you get lucky, your gun may not be so lucky). It is also possible to main or kill yourself or others if you are not so lucky. If you go into most any gun store, they will have a gun mounted on the wall that someone has "blown up". Pressure is not something to be toyed with.

Sound frought with hazard? Good, you just may turn out to be a safe reloader yet. When you are starting out, you should religiously follow powder recommendations given in your reloading manuals. Don't get cute and "make up" your own loads. Professional ballisticians working for the loading manual companies spend a lot of time and effort developing loads exactly to prevent your having to guess which powder (and how much) to use.

Powders are assigned names with letters (like Bullseye), numbers (like Accurate Arms # 5), or both (IMR-4350). It is not really safe to assume that H4895 (made by Hodgdon) is the same as IMR-4895 (made by DuPont), particularly at near-maximum loads. They are similar but not the same.

Some powder manufacturers: Accurate Arms, Hercules, Hodgdon, IMR, and Winchester.

METALLIC CARTRIDGE CASE

The metallic cartridge case (or simply "case") is the platform upon which all other components rest. The case is manufactured for a single specific chambering, for example 30-'06. The case is usually made of brass, although sometimes it is encountered in other materials like steel. Brass cases are reloadable, other cases are (for most handloaders) not reloadable. Sometimes you will encounter nickel plated brass cases, and they too are reloadable.

The metallic cartridge case is the most expensive component of a loaded cartridge, and fortunately for us, can be reused several times if we pay attention to what we're doing.

On the base of the cartridge, there is a "headstamp" which usually gives the manufacturer's identifier (W-W for Winchester-Western, R-P for Remington-Peters, etc.) as well as the chambering designation (like .357 Magnum). It is generally considered best to use cases with the same headstamp when producing a handload, as different cases have different capacities and strengths.

There are two basic case types: straight wall and "bottle neck". Examples of straight wall cases are 38 Special, 44 Magnum, and 45-70 Government. Examples of bottleneck cartridges are 30-'06, 308 Winchester, and 223 Remington.

Straight wall cases are essentially the same outside diameter at the base of the case (except possibly excluding the rim) as they are at the mouth of the case. Bottlenecked cases are not. Bottlenecked cases have a "shoulder" area, where the case diameter is reduced before the case's neck. Bullets are placed into the mouth of either straight walled or bottlenecked cases.

The areas of a bottle necked cartridge (from the bullet end working towards the primer end) are: mouth, neck, shoulder, body, head, extraction groove, and rim. There is a primer pocket in the center of the base of both straight walled and bottlenecked cartridges, into which a primer is placed.

There are five basic case rim configurations: rimmed, semi-rimmed, rimless, belted, and rebated. Refer to the section "What is Headspace" for more information about how these cases are designed to contact the gun's chamber.

Rimmed cases have no extraction groove, and the rim's diameter is greater than the case body's diameter. All of the remaining rim configurations have an extraction groove. The extraction groove facilitates removing the cartridge from the chamber once the round has been fired. Rimmed cases are typically chambered in single shot rifles, lever actions, and single shot pistols like the T/C Contender. Sample cartridge: 30/30 Winchester.

Semi-rimmed cases have a rim larger than the case's body, and also have an extraction groove. Sample cartridge: 220 Swift.

Rimless cases have a rim which is essentially the same diameter as the case's body, and also have an extraction groove. This rim type is the most prevalent in modern cartridges. Sample cartridge: 223 Remington.

Belted cases are similar to semi-rimmed or rimless cases, with the addition of a "belt" of additional brass immediately above the extraction groove. This rim type is sometimes used in "magnum" cartridges. Sample cartridge: 300 Winchester Magnum.

Rebated cases have a rim diameter smaller than the case body diameter, and also have an extraction groove. This is the least prevalent rim type. Sample cartridge: 284 Winchester.

Prior to re-using the case, it should be visually inspected for defects like cracks or bright rings fortelling case separation. If the case looks doubtful discard it.

Before we reload a previously fired case, it is necessary to "size" the case back to correct dimensions. As a result of repeated firings, it is also possible the case may have elongated, and must be "trimmed" to the correct length. Resizing the case is only one activity known as "case preparation". Case preparation is important for both safety and accuracy, so you should read up on it.

Just how is it possible for the case to change dimensions simply because the round has been fired? Pressure.

Recall from our discussion of "what happens when a round is fired": the powder ignited & the case expanded to fill the chamber. Due to the pressure, the brass "flows" in a manner similar to liquids, and assumes a tight fit in the chamber. As the pressure drops after the powder is consumed, the case will reduce in size ... but not necessarily to the dimensions we desire.

One possible change in the shape of the case is that the neck may lengthen. The shoulder may move forward so that it contacts the chamber. The case head may increase in diameter. The case may also be weakened inside; after all the brass that flowed to the neck had to come from somewhere. This last change is why we look for a "bright ring" during our visual inspection of the cases.

There are several possible undesirable outcomes if we resize the case incorrectly. We could damage the case such that it must be discarded, say by bending the neck. This would be an obvious problem. We could also incorrectly size the case so that it will not enter the chamber of our gun. Although this will be obvious when we attempt to chamber the round, it may not be detected at the time we are reloading unless we are watching for it. We could also resize a case in such a manner that accuracy suffers when the round is fired. Finally, we could resize a case so that it chambers but produces catastrophic results when fired. This is the least desirable of all possible outcomes, and is why handloaders must educate themselves, pay attention to what they're doing, and always think SAFETY.

Within certain limits, it is possible to modify the shape of a metallic cartridge case so that it becomes a different chambering. For instance, if the neck diameter of a 308 Winchester case is decreased (called "necking down") it is possible to create 7mm-08 Remington cases. It is also possible to "neck up" a 30-'06 case to a 35 Whelen case. Do not assume the only required operations are to change neck diameter, there may be other operations required such as thinning or trimming the neck.

Advanced experimenters can even create their own "new" cases, called wildcats. The 7mm TCU case is an example of a wildcat, in this instance created for the T/C Contender.

Some metallic cartridge case manufacturers: Hornady/Frontier, Remington-Peters, and Winchester-Western.

BULLET

The bullet is the whole reason for firing a cartridge; it's the part that heads towards the target, propelled by the gasses produced by burning the powder in the metallic cartridge case. There are two types of bullets the handloader will frequently encounter: lead bullets and jacketed bullets.

Lead bullets can be produced by melting lead (and possibly a few other elements) and casting the melted metal into bullet molds. Lead bullets can also be produced by squeezing lead under high pressure using a process called "swaging". Neither process will be described very much here. Lead bullets can be reused if you can recover them, and are willing to remelt and cast them. Warning: lead is toxic. Be sure you know how to handle it safely. Never eat, drink, or smoke while handling lead without first washing your hands.

Jacketed bullets are (usually lead) cores surrounded by metal jackets. The most common jacket metal is copper, although other materials are used for special purposes. It is also possible to swage jacketed bullets. Sometimes the cores are ommitted, and the bullets are called "solids". Jacketed bullets may usually be driven to higher velocities than lead bullets.

If you don't wish to create your own bullets, you can buy them. In some cases, it may be possible to save money by making your own bullets. Another reason you may wish to make your own bullets is that the bullet of your heart's desire may only be available by casting or swaging your own.

Bullets have the following areas: base, body, (possibly) grease groove(s), (possibly) cannelure, ogive, and nose.

The bullet base is called flat-based if it is the same diameter as the bullet body. If the base is smaller than the body, it is called boat-tailed. If the base is concave, it is called hollow-based. In addition, a metal disc called a gas-check may sometimes be placed on the base of lead bullets to help reduce leading, protect the base from powder gasses, and allow higher velocities.

The bullet body is the part that contacts the barrel. The body diameter is approximately the caliber size (like .308 inches) but may be slightly different for accuracy considerations. Cast bullets are frequently sized as a separate operation after they are cast.

The bullet grease grooves are normally only present on cast bullets, and contain lubricant (usually applied at the same time the cast bullet is sized). Lubricant helps reduce fouling in the barrel.

The bullet cannelure is an indented ring around the circumference of the bullet body of a jacketed bullet, into which the metallic cartridge case may be crimped. The crimp is sometimes present to produce a more consistent grip on the bullet by the case neck, leading to more consistent velocities and hence better accuracy.

The bullet ogive is the curve of the bullet's body to the nose. This curve (as well as other factors) defines the Sectional Density, which contributes to the Ballistic Coefficient of the bullet (at a given velocity), and thus partially determines how the bullet travels through the air. Sectional Density & Ballistic Coefficients are a subject unto themselves, which we will only glancingly discuss here.

Ballistic Coefficients help determine how much drop and wind drift the bullet will exhibit. Drop refers to how much lower the bullet is at some distance as compared to when it left the muzzle. Wind drift refers to how much (left or right) the bullet's path changes when a crosswind acts on the bullet during flight. Generally speaking, the higher the bullet's velocity the less time gravity and crosswinds have to affect the bullet's path, hence the lesser the drop and/or wind drift. Less drop and wind drift make hitting targets easier at varying distances and in crosswinds.

The bullet nose can be of several styles: flat nose, wadcutter, semi-wadcutter, round nose, truncated cone, spitzer, hollowpoint, and probably several others being created as I write this. Aside from how well the bullet travels through the air, nose styles also matter when the bullet impacts its target (along with other items such as jacket thickness and internal construction).

Overall, the design of a bullet can be made to emphasize various traits like expansion, penetration, ballistic coefficient, artistic beauty, whatever the designer values most. Most commercial bullets are compromises among these various attributes in mixes the manufacturers consider valuable to their customers. All things considered, bullets from the major manufacturers are simply amazing. Still, there are numerous custom bullets being made and sold for special purposes.

In terms of handloading bullets, you need to be aware of a cartridge's Overall Length (OAL). For a specific bullet placed in a specific case shot from a specific gun, there is an optimal OAL. This optimal OAL places the bullet very close (but not touching) the lands of the barrel. Even small variations in OAL when the bullet rests near the barrel's lands may cause drastic changes in pressure. Note that precisely optimized conditions for one gun may produce either dangerous or suboptimal conditions in another gun. Different bullets (even bullets with the same nose style and of the same weight but from different vendors) may lie closer or further to the gun's lands, even with the same OAL. For this reason, never simply change a round's OAL without reducing the load and working it back up.

The final bullet characteristic we will discuss is weight. Bullet weights are measured in grains, just as powder. If you will examine loading data for a particular chambering such as 308 Winchester, you will notice that different amounts of the same powder are used to produce similar velocities when different bullet weights are used. You should never switch an existing load to a different bullet weight or style without going back to the loading manual for new data, particularly when working with near maximum loads.

Some bullet manufacturers are: Barnes, Berger, Hornady, Nosler, Sierra, and Speer.