Reloading Presses
Presses are often categorized by the letter of the alphabet that they most resemble: "O", "C", and "H". The sturdiest presses, suitable for bullet swaging functions as well as for normal reloading die usage, are of the "O" type. Heavy steel completely encloses the single die on these presses. Equally sturdy presses for all but bullet swaging use often resemble the letter "C". Both steel and aluminum construction are seen with "C" presses. Some users prefer "C" style presses over "O" presses, as there is more room to place bullets into cartridge mouths on "C" presses. Shotshell style presses, intended for non-batch use, for which each shotshell or cartridge is cycled through the dies before commencing onto the next shotshell or cartridge to be reloaded, commonly resemble the letter "H".
Single stage presses, generally of the "O" or "C" types, are the simplest. They perform one step on one case at a time. When using a single stage press, cases are loaded in batches, one step for each cartridge per batch at a time. Batches are kept small, about 20-50 cases at a time, so that a batch is never left in a partially-completed state, as high humidity and light can degrade the powder. Single stage presses are commonly most used for high-precision rifle cartridge handloading, but may be used for high-precision reloading of all cartridge types, and for working up loads (developing loading recipes) for ultimately manufacturing large numbers of cartridges on a progressive press.
Turret presses, most commonly of the "C" type, are similar to single stage presses, but permit mounting all of the dies for one cartridge (or sometimes two cartridges) simultaneously, with each die being installed and correctly locked in position with lock rings onto the press at the same time. Batch operations are performed similar as to on a single stage press, but to switch dies, the turret is simply rotated, placing another die in position. Although turret presses operate much like single stage presses, they eliminate much of the setup time required in positioning individual dies correctly.
Progressive presses handle several shells at once, with each pull of the lever performing a single step on all the cases at once. Progressive presses hold all the dies needed, plus a powder measure and a primer feed, and often also include an additional station where the powder levels are checked, to prevent over or under charges. Progressive presses also often feature case feeds that will hold hundreds of cases to be loaded, and all the user has to do is hold the bullet in place over the appropriate case mouth, and pull the lever.
Shotshell presses are a special case, and are generally a single unit of the "H" configuration that handles all functions. Shotshell reloading is similar to cartridge reloading, except that instead of a bullet, a wadding and a measure of shot are used, and after loading the shot, the shell is crimped shut. The shotshell loader contains stations to resize the shell, measure powder, load the wad, measure shot, and crimp the shell.[6] Due to the low cost of modern plastic shotshells, and the additional complexity of reloading fired shells, shotshell handloading is not as popular as cartridge handloading.