Reloading: the essentials of load assembly

Nick Harvey details the critical points of reloading ammunition, from empty case to chambered round.

Brass and its excellence are crucial for all reloading operations. Everything depends upon it — safety and foolproof functioning together with the best accuracy and most power we can squeeze out of our rifles by reloading. The cartridge case holds all the ‘working’ components in proper relationship to each other prior to firing.

In reloading, cleanliness is next to godliness. Removing grease and grit from cases makes them much easier on dies and rifle chambers

A handloader aims to reuse the case. The number of times it can be reloaded and the level of performance obtainable from it depends to a certain degree upon its structural design. It is pretty well recognised that there is no fundamental difference in the strengths of modern rimless and belted cases. Due to differences in hardness and web thickness, it is not unusual to find a lot of rimless brass which will stand higher pressure than a given lot of belted brass, or vice versa.

Overall, the two types of cases can be regarded as being equal in ultimate strength, despite rumours to the contrary.

Perhaps it’s academic from a handloading standpoint, but the strongest cases manufactured today are without any doubt rimless super magnums based on the .404 Jeffery case.

Most of the factors vital to gaining the best accuracy lie in the cartridge case. Brass is the starting point for all reloading operations and all cases manufactured anywhere in the world conform to precise specifications in external dimensions. This conformity is guaranteed by the Sporting Arms and Ammunition Manufacturers Institute (SAAMI), which has also established safe maximum pressure standards for most US-made ammunition.

SAAMI SETS THE STANDARDS

When a manufacturer introduces a new cartridge, engineering drawings and specifications are filed with SAAMI, detailing cartridge and chamber dimensions, working pressures and other pertinent data. SAAMI sets the standards for safety and reliability in the design and manufacture of firearms, ammunition and components. This results in the extremely small tolerances to which ammunition and brass are being fabricated and offers some guidelines for handloading.

However, while external brass dimensions are standard throughout the industry, internal dimensions and some other characteristics such as the thickness of webs and hardness of case heads vary according to the ideas of the engineers of each individual maker, and may even show wide variation between lots from the same manufacturer.

Residue which forms in the bottom of the pocket should not be allowed to build up enough to interfere with proper seating of the primers

When case walls are made thicker, external dimensions remain standard but the volume of the cases is reduced, which has an effect on powders, loads and pressures. Similarly, up to a point, if case heads are made harder and webs made thicker, the case will withstand higher pressures and charges can be safely increased in a given brand of case beyond a point which might be safe in another brand in the same calibre.

In Australia, the handloader has brass available from many different makers, including Winchester, Remington, Hornady, Sellier and Bellot, Federal, RWS, Sako, Norma, Browning and PPU. To muddy the water even more, the head-stamp on a case doesn’t always indicate who actually made it, since commercial ammo-loading companies frequently contract out with other firms to supply them with formed brass. The only thing that will be the same is the head-stamp.

SORT YOUR CASES

This is the reason why it pays to always sort your fired cases by head-stamp and, if possible, by lot, and keep the various lots separated. If you assemble your ammo using a mixture of different brands of brass, your reloads will almost surely produce widely varying pressures from shot to shot and ruin accuracy. In an extreme case, you may even encounter dangerous pressure.

Some reloaders go to all the trouble of segregating their cases by weighing. What they are really looking for is cases having the same volume. Since the outside shape of the case is controlled by the chamber and the reloading dies, differences in wall thickness will change the case volume as well as the weight of the case.

Such painstaking efforts are simply not worth the trouble for the hunter of big game nor even varmints. The best way of ensuring uniformity in case capacity is to purchase virgin brass in lots of 100 and when they are coming to the end of their life, replace them with a fresh lot of 100.

These cases were all fired with a safe load. Primers look different because some are harder than others and don’t flatten as easily

PRIMER POCKETS

The primer pockets on new brass usually need no attention but some have the flash holes punched while others are drilled — the latter feature being preferred by many reloaders. When flash holes are punched they have tiny burrs left around them and fussy reloaders will use a pilot-style flash hole deburring tool to deburr and uniform flash holes quickly and easily. These tools use a floating pilot to guide the cutter directly toward the flash hole in the case, resulting in a clean, uniform hole every time.

With cases that have been reloaded two or three times, it pays to inspect the pockets and clean them before inserting fresh primers. Residue from previous firings may prevent primers from being firmly seated.

Some controversy still exists about the effect on accuracy of using magnum-type primers. My experience is that slightly better accuracy is obtained with standard primers when the powder used is faster than AR2209. Test both and stick with the one that gives you the best results. With both types, be sure they are firmly bottomed in the primer pocket.

If case neck thickness varies too much, cases can be evened up by inside neck reaming, but this is seldom necessary with hunting loads

NECK KNACKS

The portion of the case’s anatomy most critical to accuracy is the neck which holds the bullet. Ideally, all case necks in the lot should be exactly the same length, exactly the same thickness all around their circumference, and should grip their bullets with exactly the same tension — not too little and not too much.

Uniformity in case-neck length is simply a matter of careful trimming, deburring and chamfering. The right thickness, however, is seldom a worry for the big-game hunter since modern case necks are fairly even when you get them. In fact, I’ve never seen any advantage to be gained by reaming or outside-turning case necks for very accurate field varmint rifles.

AT THE POINTY END

Selecting the best bullet for each load relies upon the size and toughness of the game animal you are hunting. There is a staggering assortment of bullets available in all calibres, so you shouldn’t have any trouble choosing the correct one for a certain task. Any time a bullet fails to perform properly, nine times out of ten, it’s because the handloader chose the wrong bullet for the job in hand.

Most of the brochures put out by bullet makers show a cutaway view of the design of each bullet and recommend the kind of game for which it is best suited. A tough bullet which cannot expand properly on a lightly structured animal like a fallow deer is not really efficient, because it may not destroy enough tissue to put the animal down on the spot. But a fast-opening bullet may not penetrate deeply enough to reach the vitals on a bigger animal, inflicting a painful and possibly crippling wound.

Overall cartridge length is critical, not only to accuracy but also seating straightness, which ensures the bullet is going to be concentric with the bore

Elaborately constructed premium game bullets like those made by Nosler, Hornady, Swift and others may seem expensive by comparison with conventional cup-and-core bullets, but their cost for hunting is trifling in terms of the number of animals killed. Bullets are definitely not the place to start economising for hunting handloads.

PROPRELLANT POWDER

After you’ve chosen the right bullet, the powder should be selected on the basis of what it is, what it is expected to do, and the ballistic conditions under which it has to perform.

Smokeless propellants cannot be rigidly classified into neat little niches as being either fast or slow burning. Their rate is influenced by a number of factors including the ballistic conditions under which the propellants are ignited. A specific powder — any powder — may burn faster or slower according to the amount of pressure it develops as combustion converts it to hot, expanding gases. The burning rate is influenced by factors such as case capacity, case shape, bullet weight and diameter, and the diameter of the bore in the barrel. Other important influences include the length of the barrel and, consequently, the time in which the propellant has to do its work.

Handloading ammunition — There’s a huge range of reloading manuals available, though only a few are needed

By referring to your reloading manual you can select the powder which gives the highest velocity for your chosen bullet. In many cases the most efficient powder is one which can safely be loaded in a charge which fills the case to the base of the seated bullet.

This is not to imply that there are no good, accurate loads which deviate slightly from this set of specifics. Still, I would recommend you double-check any load that departs to any extent from the general rule, especially a load you may have arrived at without consulting some more experienced source of load data.

BURNING RATES

Smokeless propellants burn at a rate that is directly controlled by the pressure at the moment. Any given powder burns faster in a round loaded for 60,000psi than one at 40,000psi by a ratio of 3:2. The exact formula is an exponential differential equation (calculus). It is also important to realise that as pressure goes down, powder burning rate drops to zero. Powder won’t burn except at reasonable pressures, and it won’t start burning until pressure is elevated.

All colloidal smokeless powders burn at the same basic rate. The total surface that is burning fixes the energy release. If a large enough charge of bigger granules has the same surface area as a lighter weight of smaller ones, they will both release energy at the same rate and give the same peak pressure, but not the same bullet velocity.

The charge that weighs more and contains greater energy will impart more energy to the bullet under these conditions, because it will burn longer. However, using a larger charge of a slower burning powder only succeeds when the barrel is long enough to harness the energy.

Nitroglycerine adds to powder energy. Double-base powders burn hotter, putting more energy into the bullet.

Modern magnums have powder space for more than enough of any suitable propellant and do not need the boost of extra strength powder.

Work from reliable, tested loading data and use the powder recommended for your bullet weight in your cartridge. Do not exceed the maximum charge weights recommended, and you will not get into trouble.

IN THE HOT SEAT

The final operation is to seat the bullet into our sorted, cleaned, chamfered, deburred, primed, charged cartridge cases. Many reloaders get to this stage and then hurry to plug their bullets into the cases. This negates to a degree all the work they have done previously. There’s more to bullet seating than just working the handle on the loading tool.

Correct bullet seating requires paying attention to two important factors: seating depth and concentricity. Finding the proper seating depth for your rifle and bullet takes a little doing.

If you chose a heavy bullet that’s long for its calibre, it will have to be seated deeper in the case, reducing the powder space

Only seldom will the standard overall length — the overall length to which factory cartridges are loaded — suit our purpose. The handloader may want to seat the bullet deeper or shallower for one reason or another.

In a bolt-action repeater, the length of the magazine imposes an overall length limit on some cartridges, but the throat length of a chamber will also limit overall cartridge length. If the bullet is seated so far out that it is jammed solidly into the origin of the rifling — the lede — a serious jump in pressure may happen because the bullet is delayed for an additional fraction of a second before it begins to move forward under the impetus of the expanding powder gases. If the bolt is opened without firing the round, the bullet may be held firmly enough by the rifling to be pulled out of the case, spilling powder all through the action and requiring the use of a cleaning rod to remove the bullet.

Seating too deeply can also increase pressure by decreasing the volume of the combustion chamber within the case. It’s rarely enough of an increase to cause a problem, but accuracy suffers because of the extra distance the bullet must jump to reach the rifling and because it usually reaches the lede yawing. It is cockeyed when it gets driven through the bore and its centre of form no longer coincides with its centre of rotation, so it leaves the muzzle in a state of dynamic unbalance and the shot goes wild.

There are several ways to determine the amount of clearance. The easiest is to take a fired case, run it into the sizing die just far enough to size about 2.5mm of the mouth, and insert a bullet in the neck with the fingers. Seat the bullet as long as possible, carefully chamber the dummy round and close the bolt. Contact with the lands should push the bullet into the neck so that the overall cartridge length can be measured.

The wise hunter runs all his reloads through the rifle’s chamber before taking them on a hunt

Use this round as a gauge to set the seating die to seat bullets from 0.76-1.52mm (.030 to .060”) deeper for a varmint gun; for game-hunting loads I recommend the bullet be seated so that it is 0.80-1.59mm (1/32 to 1/16”) short of the lands.

My big game rifles are free-bored — they have throats longer than normal. Bullets can be seated shallower for a longer overall cartridge length, adjusted so that they will just fit in the magazine.

Finally, run every single round through the chamber before heading off on a hunting trip. That’s the best advice I can give you.