For many reloaders, the primary goal is to create ammunition that meets safety standards, is cost-effective, and reasonably accurate by following standard reloading practices. However, for those who prioritize accuracy, such as competitive shooters, special reloading techniques are employed, all with the ultimate aim of achieving maximum uniformity among each finished cartridge.

The concept of uniformity in ammunition means that all bullets exit the muzzle at the same point within the barrel’s vibration pattern, resulting in more consistent shooting. Uniform loads also minimize shot-to-shot variations in bullet velocity, which is crucial for maintaining consistent downrange trajectories. To illustrate, a change in muzzle velocity from 2700 to 2770 fps with a typical .30-caliber target bullet can lead to a four-inch deviation in drop at 500 yards and a substantial 23-inch change at 1000 yards—enough to significantly affect accuracy. Hence, long-range shooters typically strive for a standard velocity deviation of no more than 10 fps.

Achieving uniform ammunition necessitates uniformity in each component and process involved. In this series of articles, we will begin by exploring the importance of uniformity among casings in reloading.

Cases

The objective of case preparation is to establish a set of cases that exhibit uniformity in various aspects, including volume, length, neck and wall thickness, primer pockets, flash holes, and more.

It is important to acknowledge that different brands of cases within the same caliber can differ in dimensional consistency, strength, and other factors. Consequently, if achieving specific velocity is a concern, opting for a case brand with a lighter average weight can provide greater internal volume. This increased volume allows for the loading of more powder while maintaining safe pressure levels, ultimately leading to higher velocity.

Furthermore, it’s crucial to consider that military cases designed for commercial rounds typically have thicker walls, resulting in reduced case capacity compared to their commercial counterparts. To compare the case capacities directly, a useful technique involves weighing cases before and after filling them with water, with the difference in weight indicating the case capacity in grains of water.

The initial step in case preparation involves sorting cases of a specific caliber based on criteria such as manufacturer, date of manufacture, or lot number, as well as the number of times they have been reloaded. Once the sorting process is complete, each case should be carefully inspected for any defects, such as off-center flash holes or dents in the neck or shoulder. Some benchrest shooters take it a step further by measuring the neck thickness at various points and discarding cases that exhibit a variance of more than .001 or .002 inches. The rationale behind this is that variations in neck-wall thickness can extend into the case body, leading to an off-center combustion chamber and an internally imbalanced case that will not respond uniformly to the stresses of firing.

To achieve maximum uniformity, an additional sorting operation is often undertaken. This involves sorting once-fired cases from the same lot by weight, typically using a reloading scale, after performing tasks such as trimming, neck turning, and ensuring uniform primer pockets and flash holes. By completing these steps before weighing, any differences in case weight can be attributed to variations in case volume.

In benchrest shooting, many shooters classify their cases into groups with weight variances of no more than one grain, and sometimes even less. Cases within the same weight class are believed to possess similar capacities and are typically fired together. However, it is worth noting that some successful match shooters in disciplines other than benchrest do not weigh cases at all. Instead, they rely on shooting tests to separate the cases that perform well from those that produce flyers. Combining a sorting method based on weight with additional culling based on shooting groupings seems to be an effective approach.