According to FN : The plating process FN uses is a "hard chrome" plating instead of a "soft chrome"
plating. All M-240, M-249, P-90/PS-90, FsN, F-2000/FS-2000 and SPR firearms have the same hammer forged, hard chrome plated barrel process. This is to ensure barrel life rather than to prevent corrosion. The reason the barrels are so accurate is because the inside rifling contour is much smoother and precise than a button cut barrel and it does not need to be straightened. This process is very expensive from a machinery point of view and most smaller companies cannot afford to do it.
Don't confuse the soft chrome process of the M-16/AR-15 with the other. They are two very different products. Also, most soft chrome plated barrels are button cut which is not as smooth as a hammer forged barrel to apply plating to and the plating is there to keep the bore from rusting.