Economy, increased accuracy, and improved performance are common motivations for hand loading cartridges. Reloading fired cases can save the shooter money and provide the shooter with more, and higher quality ammunition within budget. Reloading may not be cost effective for occasional shooters, as it takes time to recoup the cost of the equipment, but those who shoot on a regular basis will see benefit as the brass case (the most expensive component) can be reused many times (with proper maintenance). Besides economy, the ability to customize the performance of the ammunition is a common goal. Precision target shooters seek the best achievable accuracy, as well as the best shot-to-shot consistency.

There are three aspects to ballistics: internal ballistics, external ballistics, and terminal ballistics. Internal ballistics refers to things that happen inside the firearm during and after firing, but before the bullet leaves the muzzle. The hand-loading process can increase accuracy and precision through improved consistency of manufacture, by selecting the optimal bullet weight and design, and tailoring bullet velocity to the purpose. Each reloaded cartridge can have each component carefully matched to the rest of the cartridges in the batch. Brass cases can be matched by volume, weight, and concentricity, bullets by weight and design, powder charges by weight, type, case filling (amount of total usable case capacity filled by charge), and packing scheme (characteristics of granule packing).

In addition to these critical items, the equipment used to assemble the cartridge also has an effect on its uniformity/consistency and optimal shape/size. Dies used to size the cartridges can be matched to the chamber of a given rifle. Modern hand-loading equipment enables a rifle owner to tailor fresh ammunition to a specific firearm, and to precisely measured tolerances far exceeding the comparatively wide tolerances within which commercial ammunition manufacturers must operate. In the precision rifle community (visit Tacticalmatches to talk to some of the best precision shooters in the nation), a common topic is, “What is the best possible ammunition?” Some precision shooters emphasize that hand loads excel over the mass-manufactured precision rifle rounds. The following will help us to determine an answer to the question.

Hand load accuracy theory 

Every rifle barrel develops some sort of harmonic vibrations when the cartridge is fired. A rifle barrel’s vibration can also be somewhat described as a three-dimensional wave or corkscrew movement, and is caused when the bullet is accelerated into a rapid spin caused by the rifling inside the barrel. This can be seen on high-speed film, and it is pretty impressive that we are able to hit anything with the amount of barrel movement present.

It is impossible to fully eliminate all barrel movement, even if the rifle has one of the thickest barrels in production. Even thick barrels will vibrate with every shot and any velocity variation will alter where the muzzle is finally located when the bullet exits.  The random movement of the muzzle will give some sort of deviation and rise to increased group size, which is one of the reasons we see larger groups at distance.

The most experienced rifle builders will always allow the barrel to flex, given the idea that if the barrel’s movement cannot be eliminated, the next best solution is to have flex/harmonic consistency. Some of the best rifles in production have their actions and the first inch or so of the rear of the barrel bedded tightly into the stock to hold the receiver firmly, with the remainder of the barrel free-floated. In addition, short, thick barrels have wide(r) nodes, so velocity isn’t as critical to achieving a sweet spot.

Since the velocity of the bullet passing through the barrel affects the way it flexes, accurate loads should deliver as consistent a velocity from shot to shot as is possible so that the bullet exits the muzzle at the same point in the ‘flex’. You can control this to a certain degree, but is impossible to entirely eliminate shot-to-shot velocity deviation. At around a variation of 10 to 12 f/s, it may become almost impossible to reduce the effect any further.

It has long been understood that barrels perform best within certain velocity ranges.  These velocity ranges are commonly referred to as a ‘harmonic nodes’ or ‘sweet spots.’ The reason for this is that the tensile strength (or the ability to resist further bending) of the metal alloy increases as it moves further away from its static state. The barrel gets stiffer when it is forced to the extremity of its movement.