The Prototypical 
Guide To 
Paintball Guns 
STOCK CLASS GUNS
 PG

 From the Proto Collection 1998
Manufacturer Benjamin Sheridan / PMI
Action Stock Class Bolt Action
Configuration Upper Bore and Lower Valve
Valve Style Sheridan Based
Caliber 68
Velocity Adjustment None
Feed Type Horizantal Feed
Barrel Non Removable 6.5" Brass
Gas Source 12gram Quick Change
Features:

Options:

Protobable - You could consider this the older brother to todays PGP.  The action worked by twisting the back cap, pulling it back (which loads a paintball and cocks the gun), push the back cap back in and twisting in to the lock position.  Many of the earlier PGP's where just PG's with a pump.