It has a gas-actuated piston-driven long-stroke operating system derived from the SIG SG 540 series of rifles , which uses burnt powder gases vented through a port in the barrel to power the weapon 's moving parts .
PRON VERB DET VERB ADJ ADJ NOUN NOUN VERB ADP DET PROPN NOUN NUM NOUN ADP NOUN , DET VERB VERB NOUN NOUN VERB ADP DET NOUN ADP DET NOUN PART VERB DET NOUN PART VERB NOUN .