SPR/MK-12 Barrels 17.9″: Bartlein-SS 4 Groove


Length              17.9″
Caliber             .223/5.56
Gas Block        .750

  • 1-7 Twist
  • 1-7.7 Twist
  • MID Length
  • Intermediate Length
  • Rifle Length
  • CLE
  • Wylde
  • 1/2x28
  • 5/8x24
  • Polish(standard)
  • Bead Blasted
  • Cerakote C-Series(cold cure)
  • Add Matched Bolt
  • Customer Supplied


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, finish and add 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.


Additional information



Gas System Length

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Chamber Type





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Matched Bolt



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