But yes in NPPL
7.01 Marker Specifications. Players may use a single, 68 or .50 caliber, pump or semiautomatic paintball marker, which consists of a single barrel and single trigger. All Paintball Markers shall only operate in semi auto or pump mode and may not operate in other discharge modes such as burst, enhanced trigger, trigger bounce or fully automatic discharge mode during league play. Paintball markers may not fire over 15 balls per second. See ASTM F2272-03
As for small tournaments, it would prob be fine but just ask the field.