barrel swap colt m4


Full Member
Full Member
Feb 16, 2017
i bought a jp supermatch 223 wylde 16" barrel to try on my colt m4. discovered that the gas port is further forward than my stock barrel, which obviously has the big iron front sight/gas block combo with handguard. i have not done a lot of ar work, can i simply get a longer gas tube and a adjustable gas block and a 15" rail to make this barrel work? forgive me if this is an elementary question. i did email jp but have not gotten a reply yet.


Full Member
  • Jan 15, 2005
    Gulf Coast, FL
    Yes you'll just need the appropriate length gas tube, a gas tube roll pin, and and appropriate diameter gas block if your current barrel has a FSB. I would suggest getting a good adjustable gas block (JP, Superlative, and Seekins are the best IMO) so you can perfectly adjust the system. A long rail is desirable and 15" on a 16" barrel will keep the hand guard just behind the shoulder of the muzzle thread in case you're running a larger can than the forend will accommodate.

    I'd also suggest using appropriate size roll pin starter and driving punches as they will deform and the gas tube pins can be a little finicky with alignment driving home.