Accuracy Systems, Inc. Click for the BBB Business Review of this Guns & Gunsmiths in Byers CO 1661 Behrens RD
Byers, Colorado 80103
Tel: (303) 822-6849 Fax: (720) 367-5095
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Harmonic Barrel Stabilizer II Installation Instructions

Tightening Torque for Gas block and clamp screws is 40 Inch Pounds.

Harmonic Barrel Stabilizer II Instructions

  1. The First Thing We Request. Do not try to rotate the Gas Pressure adjustment screw referred to from here on as the (G.P.A.S). on the front of the gas block (Illustration #1).
  2. You must first install your gas bushing from your current Ruger factory gas block into the new gas block.
  3. The Stabilizer bar comes Pre-installed into the face of the gas block. The bar is 6061 Aluminum alloy so if you are ever going to remove the bar using a wrench make sure you take precautions to pad the wrench so you do not mar the finish.
  4. The front clamp works and looks best if it is positioned just behind the grove on the front of the Stabilizing bar (Illustration #2). Do use red Loctite on the two clamping screws if you do not want them coming loose.
  5. Harmonic Barrel Stabilizer II Instructions Harmonic Barrel Stabilizer II Instructions
  6. When you receive the HBST II the Gas Pressure adjustment screws - set screw is tightened. Before making any adjustments you need to loosen the set screw.
  7. When you are completed making your adjustment snug tight the set screw so you do not damage the G.P.A.S threads! If you apply too much pressure you will crush the threads on the G.P.A.S. and you may not be able to adjust it any more. There will be a cost for us to fix it of $20.00.
  8. When installing the bushing into your new gas block MAKE SURE that the gas bushing will drop all the way in and bottom out in the gas pipe recessed hole.
  9. If the gas bushing does not drop all the way in and seat into the recessed hole you will damage the gas pipe when you go tighten the gas block to the barrel.
  10. If the gas block will not sit flush on the barrel then you do not have the bushing seated correctly or the gas bushing is too long. If the bushing is too long it may have to be trimmed in length. ** When trimming the gas bushing please refer to our website under: PRODUCT INSTRUCTIONS Trimming gas bushings for Harmonic Barrel Stabilizer II, Adjustable Gas block & Non Gas blocks.
  11. Once the bushing is seated correctly and the gas block is installed onto the barrel it is time to test fire your rifle.
  12. The G.P.A.S. is pre-set fully open. DO NOT BACK IT OUT ANY FURTHER!! If the rifle is throwing the spent casings further than you would like you will need to start to close (turn clockwise) the G.P.A.S. one 16th turn at a time until you achieve your desired position. A little turn can make a big change so go slow.
  13. ** If you are not sure where full open should be because you have moved the G.P.A.S. during installation turn the G.P.A.S. clock wise till it stops, that is fully closed. When fully closed there is no gas delivered to the operating rod and the rifle will not cycle. Then follow these instructions:
    1. Remove the gas block if you have already installed it. Then with the gas bushing removed look into the hole in the gas pipe where the bushing would sit.
    2. Make sure you are in a well lit area.
    3. Then looking into the hole you should see the gas pressure adjusting screw.
    4. Back it out till the tip of it is flush with the side of the gas port hole and that will be fully open.
    5. Turning Clock wise count the turns till you can see the screw closing the Gas port hole that is fully closed. **Remember how many turns you have taken so you know the maximum amount of turns it will take to be fully open. Do not turn the G.P.A.S. out any more than the number of turns it took to close it. If you do you will loose gas pressure and could loose the screw as well!! When fully closed there is no gas delivered to the operating rod and the rifle will not cycle. At that point you can turn the G.P.A.S. a little Counter clock wise until it starts to cycle, but no more than your turn count that will be fully open.
  14. Some rifles may require that the gas port hole be enlarged. The gas port is the hole in the barrel that the gas passes through into the gas block. It is very easy to do. Please call us and one of our qualified gunsmiths will walk you through the 2 minute process. This process is for the exception rifle that will not cycle.

  15. Harmonic Barrel Stabilizer II Instructions Harmonic Barrel Stabilizer II Instructions

    Harmonic Barrel Stabilizer II Instructions Harmonic Barrel Stabilizer II Instructions

    Contact us at: Accuracy Systems, Inc. 1661 Behrens Rd. Byers, CO 80103
    Phone 303.822.6849 or
    Visit us at

    Revised 11/7/2016


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