Handloading

Handloading is the practice of making firearm cartridges by manually assembling the individual components (metallic/polymer case, primer, propellant and projectile), rather than purchasing mass-produced, factory-loaded commercial ammunition. Handloading using previously fired cartridge cases or shotshells is called reloading (should not be confused with the reloading of a firearm with cartridges, such as by swapping detachable magazines, or using a stripper clip or speedloader to quickly insert new cartridges into a magazine). While the root "loading" refers to the filling of muzzle loading firearms with propellant (originally with black gunpowder or less commonly smokeless powder) and a bullet. Most of the actual handloading process involves the cartridge case and its preparation, because unlike the propellant, primer and projectile (bullets, shot and slugs), which are all single-use consumables, the case is the only reusable component and its shape, internal capacity and crimping tension are crucial factors influencing the internal ballistics of the cartridge.

The term handloading is the more technical term that refers generically to any manual assembly of ammunition cartridges, although reloading is often used interchangeably since handloading more often than not involves used cases and the loading techniques are largely the same regardless whether the cases are brand new or having been previously fired (used). The only differences lie in the initial preparations — new cases are generally ready for loading straight out of the box, while previously fired cases often need additional procedures to prepare them for loading. This can include basic operations such as removal of expended primers ("depriming"), case cleaning (with water, ultrasound or abrasive media to remove fouling and/or corrosion residue) and/or burnishing/polishing, deburring and resizing to return the case to it's pre-fired shape or to reform from fire forming or to experiment with custom modifications (wildcatting), trimming the cases to length, or more advanced operations such as reshaping (to correct any pre-existing deformations, or for caliber conversion).

There are also other informal terms that describe specific situations of handloading, such as hot loading (filling the case with more propellant charges than recommended) and underloading (filling with less propellant than recommended), the former often in "wildcat" experiments (and can be potentially dangerous due to excessive pressure), and the latter often in the production of blanks and less-lethal cartridges with wax/rubber/plastic projectiles and can result in squib loads. Dummy rounds are also made via handloading techniques by completely skipping the propellant loading, primer installation and by marking the cartridge (usually by drilling holes in the case or using specific colors).

Handloading is a popular practice among shooting sport enthusiasts, especially those involved in precision-focused benchrest or long-range shooting. It is a method of accurizing that involves trial-and-error experiments with different combinations of projectile (different weights and profiles), propellant quantity, propellant types/brands, seating depth and whether to crimp the bullet or not. These changes are done one at a time because changing more than one variable at a time is usually self defeating. Each cartridge combination (known as a load) is then field-tested with a chosen firearm (usually the gun the load is intended for) and fine tuned (again by changing one variable at a time) until a combination with minimal variations in muzzle velocities (measured with chronographs) and the smallest shot grouping is achieved. Best practices dictate that the reloader keep all load and performance data so loads can be readily reproduced in the future as well as not repeating previous, less than optimal, loads. Also, all reloaded ammunition is to be labeled with all data to avoid confusion in the future.