Christensen Arms Modern Precision Rifle Chassis Black Short Action 17″ Handguard. The Christensen Arms Modern Precision Rifle Chassis is the same ultra-lightweight adjustable system found on the Modern Precision Rifle now offered as an individual component. Crafted from 7075 billet aluminum with carbon fiber components this chassis system features Magnelock Technology and a 17″ FFT carbon fiber handguard with M-Lok compatibility. With an adjustable cheek riser and length of pull this chassis system is perfect to start your next MPR workbench project.