An electropneumatic paintball marker is a paintball marker that uses a pneumatic solenoid to actuate the hammer and/or bolt's movement.
The origin of the electropneumatic paintball marker is the subject of a patent dispute, but is generally acknowledged to have happened more or less simultaneously with the introduction of WDP's Angel and PneuVenture's Shocker, marketed by Smart Parts, both in 1996. The markers were operated differently; they were similar only to the extent that they both make use of one or more microswitch-controlled solenoid valves.
The Shocker used two solenoid-operated control valves in order to obtain separate controls over the ball loading sequence and the air delivery sequence. The Angel made use of a linked hammer and bolt assembly, which permitted the use of a single solenoid to actuate the entire firing sequence by controlling a piston that powered the hammer/bolt assembly forward, simultaneously chambering a paintball and releasing the propulsion gases at the end of the hammer's stroke.
The twin-solenoid arrangement of the Shocker permitted slightly lower operating pressures to be used, however the drastically simpler arrangement of the Angel provided a faster firing sequence, which ultimately proved to be favored by the players and as a result the basic operating principle behind the Angel has remained unchanged (indeed, it has even been copied many times over by a series of "stacked tube electros"), whereas the Shocker has gone through a series of revisions that culminated in a complete redesign in 2003, and now uses a single solenoid powering the increasingly popular mechanical configuration known as a "spool bolt".
It is also worth noting that while these two markers essentially tied for first electropneumatic markers to market, both designs were pre-dated (by years in some cases) by a series of homemade electropneumatic "kits" that modified pre-existing markers such as the or Sterling.
The increased availability and use of these markers also encouraged a movement that had already been chafing at the previous technology advances of paintball. These players desired a return to the days of pump markers, ten round capacity, and 12-gram CO2 "powerlets". The movement eventually became what is known today as "".