Adjusting UDP-9i suppressor ports


If you have any doubts in your ability to perform the following actions, stop immediately and seek assistance from a qualified gunsmith. If you need clarification on any of the steps below, please contact us to speak with a member of our support team.

Always wear proper personal protective equipment (PPE) including adequate eye protection when servicing a firearm.

Click here to download a copy of the UDP-9i User Manual

Your UDP9i comes with a fully adjustable port system. By opening or closing the 15 available threaded ports, the velocity of a given round can be reduced by up to 125 fps (feet per second) from its maximum velocity.

  • If you plan on shooting supersonic ammo, but want maximum sound reduction, open all of the ports allowing complete system venting.
  • If you plan on shooting subsonic ammo and desire to maintain as much velocity and muzzle energy as possible, close off all ports to eliminate any system venting.
  • If you desire something in between, then use the set screws to open or close the ports to reach the desired velocity or muzzle energy for a given round.

To close ports

  1. Remove magazine, and clear chamber.
  2. Remove Socket head allen screws that attach handguard to mount, place them in a safe location nearby.
  3. Remove handguard and set aside.
  4. Unscrew end cap from end of suppressor core, and set aside.
  5. Rotate outer tube 1/4- 1/2 rotation while sliding tube over core ( Note, if cleaning intervals have not been maintained, tube may require multiple rotations while sliding to remove due to carbon buildup. See cleaning instructions for cleaning intervals and methods).
  6. Use the provided 3/32" T-Handle Hex wrench and thread in one of the provided 10-32 set screws till it bottoms in the hole.
  7. DO NOT over-tighten the screws as you can strip the thread in the barrel.
  8. Hand snug the set screws for the time being.
  9. Perform the previous 7 steps in reverse order and test for your desired requirements.
  10. Once the optimal setup is achieved, perform previous steps and use Loctite compound (or rockset) to keep screws from backing out during prolonged use.
  11. Test fire the firearm.