barrel stared life as a 20" chrome lined gov profile. i had a local machinist cut it back to 18 inches and thread it standard 1/2 x 28 tpi and re-crowned. shoots about 2" groups with xm193 and q3131a at 100 yards and is reliable in feeding and extraction. barrel twist rate is 1 in 9.
the gas port was opened to .090" and cycles the following ammo with no problems; south african, xm193, q3131a, q3131, S&B
comes with gas tube, barrel nut assembly and 5 port phantom FH. price is $165 shipped.
thanks, scott in tucson