Loaders

Loaders, also commonly known as hoppers, hold paintballs for the marker to fire. There are many variations, but the primary types are gravity feed, agitating, and force-feed. Stick feeds are also a means to hold paintballs, though they are not, strictly speaking, considered "hoppers".

While agitating and force-feed hoppers facilitate a higher rate of fire, they can fail due to dead batteries as well as contact with moisture, which keeps many woodsball and scenario players away from them. Ball breaks pose a problem for all hoppers, regardless of design. When a paintball leaks paint into the hopper from a break in the hopper, it can cause the gelatin shells of the paintballs to deteriorate and sometimes stick together.

Stick feed
Stick feeds are primarily used on pump and stock-class markers. They consist of simple tubes that hold ten to twenty paintballs. Stick feeds are usually parallel to the barrel and the player must tip (or rock, leading to the term "rock n'cock") the marker to load the next paintball. Some stick feeds are vertical, or at an incline to facilitate gravity feeding, though this contravenes accepted stock-class guidelines.

Gravity feed
Gravity feed is the simplest and cheapest form of hopper available. Gravity feed hoppers consist of a large container and a feed tube molded into the bottom. Paintballs roll down the sloped sides, through the tube, and into the marker. These hoppers are limited to feeding 8 balls per second reliably. Gravity feed hoppers are very cheap, since they are made of only a shell and a lid, but can become jammed easily as paintballs pile up above the tube. Occasionally, rocking the marker and hopper can keep the paintballs from jamming at the feed neck.

This problem is made worse when using a modern fully-electronic marker. Most economic and mechanical markers use a blowback system for recocking, or other methods where a large reciprocating mass is involved. This will shake the balls in the hopper slightly, facilitating gravity feed. A marker with both electronically controlled recocking and firing will often exhibit no shake whatsoever while operating. Because of this, small packs in the hopper are not broken up, and feeding problems are made worse.

Agitating
Agitating hoppers use a propeller spinning inside the container to agitate, or stir up, the paintballs. This prevents them from jamming at the feed neck and feeding more rapidly than equivalent gravity feeds. Older tournament-level hoppers are of the agitating type, since the higher rate of fire requires a more advanced and consistently-loading hopper.
Unlike the previous types of hoppers, there are two types of Agitating Hoppers: those with "eyes" and those without. These eyes consist of a LED (light emitting diode), and a photodetector (typically a phototransistor or photodiode, which is sensitive to light) inside the neck (tube) of the hopper and are often inside electronic markers. Eyes are used to detect whether a ball is present or not. In a marker, the eyes will keep the gun from shooting until a ball is fully loaded into the chamber. In a Hopper the eyes detect when a ball is not present to cause it to turn. Agitating hoppers without eyes will run down batteries and may bend or dent paintballs which will in turn cause a short, less air efficient, skew shot. Agitating hoppers with eyes will only spin whenever there is not a ball, which causes less chance of damage and longer battery life.

One notable hopper is the Tippmann Cyclone Feed system. It could be called a hybrid agitator/force feeder, because it contains both in the form of a five point star shaped piece that captures five balls and forces them into the chamber when the bolt is open. It is used on the Tippmann A5, X7, and can be installed on the 98 Custom. The Cyclone system uses excess gas tapped from the power tube to force feed a ball into the gun. There are several benefits to this, it does not require batteries, is not affected by water, and it only cycles when the gun fires. Contrary to popular belief, the Cyclone does not require more CO2/HPA, the gas used to drive it would just be released into the body of the marker if it were not used. Its ratchet does wear out over time, however, and to combat this there are after market aluminum parts available.

Force-feed
Force-feed hoppers utilize an impeller to capture paintballs and force them into the marker. The impeller is either spring-loaded or powered by a belt system, allowing it to maintain constant pressure on the stack of paintballs in the feed tube. This allows force-feed hoppers to feed paintballs at high speed (over 22 balls per second), since the mechanism does not rely on gravity to move paintballs into the feed neck. Force-feed hoppers are the dominant form of hopper in tournament play, as they are the only loader capable of keeping up with the high rate of fire found in electropneumatic markers.

Some markers, such as those manufactured by Real Action Paintball, use force-fed loaders shaped as firearms magazines. These are preferred when a low profile is required, as in woodsball 'sniper' positions. Even more unusual are fully-contained magazines, incorporating both a source of propellant gas and force-fed paintballs such as those used in the markers manufactured by Tiberius Arms.

The newest type of force feed hoppers communicate wirelessly with the marker's electronics via radio frequency. This allows the hopper to begin feeding paintballs before the pneumatic system of the marker has even begun cycling the next shot. Not only does this system almost totally eliminate mis-feeds, but it can greatly increase the speed of the loader and increase battery life due to the loader only being in operation when the marker is preparing to fire, as opposed to the continuous operation of many other loaders. An example of the radio frequency activated hopper is the DXS/Draxxus Pulse. It should be noted, though, that Procaps (the maker of the Pulse) is being sued by NPS (maker of the Halo B, another force-fed hopper) for alleged intellectual property theft of the magnetic aspect of the RF Chip and the internals of the Halo hopper. DXS/Draxxus has halted production of the Pulse, and its future production is unclear. Furthermore, use of this feature requires that a chip be soldered to the electronics board inside the marker. Many new marker manufacturers and aftermarket electronics companies have announced that their markers/boards will support this new technology.