The MPA BA ESR Chassis offers functionality in military, law enforcement and various competitive shooting applications. MPA BA Enhanced Sniper Rifle (ESR) Comer, Ga. (Ammoland.com) – MasterPiece Arms (MPA), manufacturers of the MPA BA Rifles and Chassis Systems, will unveil its new MPA BA Enhanced Sniper Rifle (ESR) Chassis in booth 2716 at SHOT Show