The MK 17 is the second part of the FN SCAR family of weapons. A selective-fire semi-auto and full-auto 7.62x51mm NATO rifle using a short stroke gas piston, the MK 17 also offers three interchangeable barrels that can be switched by the individual operator in just minutes for CQC, tactical and precision fire roles. Controllability is a hallmark of the MK 17, firing controlled pairs easily even in full-auto mode. Like the MK 16, the MK 17 remains a completely ambidextrous rifle design with a fully free-floating barrel, multiple integral MIL-STD 1913 mounting rails and a telescoping, folding buttstock with adjustable cheekpiece. All MK 16 and MK 17 rifles offer 98% parts commonality within the same caliber and 82% parts commonality between rifles of different calibers, thus simplifying maintenance, armorer training and logistic support requirements.