Heckler &Koch ~ HK91 SACO 1976 with Polygonal Bore ~ .308 Win.

This 1976 Heckler & Koch HK91 imported by SACO with a polygonal bore is a rare, early-generation collector's piece. These mid-1970s models feature unique polygonal rifling instead of traditional lands and grooves, offering longer barrel life and easier cleaning, making them highly prized by vintage firearm collectors. The 1976 polygonal bore has a rounded-profile rifling rather than sharp edges. This creates a tighter gas seal which can yield slight velocity and accuracy increases.