Use in Paintball Markers
The term "ball detent" is also used when referring to a mechanism in paintball markers designed to prevent the paintball from rolling out of the firing chamber before being fired. Some designs are similar to those outlined above, with a cartridge utilizing a ball bearing in a bore with spring pressure. The cartridge is installed perpendicular to the barrel bore axis, just ahead of where the ball rests before being fired. Other designs use elastic rubber protrusions that block the ball until it is pushed over it by the bolt. Some designs use precisely calibrated rings or "barrel sizers" that are selected to have a slightly smaller inner diameter than the outer diameter of the paintballs being used. They rely on simple constriction of the bore to prevent paintballs from rolling through them from the force of gravity. When the marker is fired, the air pressure pushes the ball through the bore, causing it to compress enough to pass through. Paintballs have varying diameters depending on a number of factors; this type of ball detent must be sized correctly to avoid compressing the paintball too much, causing it to burst. If a too large sizer is selected, balls may roll through it.
The cartridge and elastic rubber protrusion type detents are primarily used for open bolt markers, or on closed bolt markers to prevent double feeding (feeding more than one ball when the bolt is open for loading). Closed bolt markers generally use the constriction method to prevent "roll outs". A roll out is a frustrating malfunction where the ball completely rolls out of the barrel, causing no paintball to be fired when the trigger is pulled. A partial roll out is when the ball rolls partially through the barrel, causing reduced velocity.
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