The only 16" barrel on the market at this time that fits the M4-22 Micro Elite Pistol (or any Tippmann M4-22) is the Tippmann OEM 16" fluted barrel. We carry them at Resilient Arms and they have been flying off the shelf this week with the ATF brace ruling. The 16" barrel is actually a nice option to have, brace ruling aside. The barrel change on the M4-22 is about a 10 min. job and I'm happy to help out with any questions from people who call or email.
