This barrel comes standard with M4 Feed Ramps, MID or Intermediate gas system, 1/2-28 or 5/8×24 threaded muzzle, and the proper OPS, Inc. muzzle contour for OPS, Inc. collar.
Chamber type, gas system , thread and match bolt is your choice.
Please Note, barrels are finished to your specs after you order them. Currently, we are at about 3-4 weeks turn around for SPR barrels. We do hit delays from time to time and it may take an additional week.