Adams Arms Gas Piston Conversion Kit Installation

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The following is a video transcription depicting the Adams Arms gas piston conversion kit installation.


You will need the following tools to install the Adams Arms retro fit gas piston system:


  • 1/8″ Hardened Punch
  • 5/32″ Allen Key or Allen Key Socket
  • 3/4″ Wrench
  • Metal Hammer
  • Bench Vise
  • Torque Wrench



Depending on your upper assembly and your abilities you may also want:


  • Armor’s Wrench
  • Dremel Tool with Cutting Wheel
  • Plastic or Rubber Hammer
  • Handguard Removal Tool
  • AR15 Vise Block
  • Front Sight Bench Block
  • Snap Ring Pliers
  • Feeler Gauge


For the terms of this video DI stands for Direct Impingement System and refers to any parts on an AR15 or M16 that push hot or dirty gases into the upper receiver to cycle the rifle’s action. This is a complete upper receiver. This is a complete lower receiver. Before performing any step of the Adams Arms installation check your firearm to see if it is unloaded and on safety. Drop any magazines you may have in the AR and manually cycle the action multiple times to ensure no round is in the chamber. Turn the safety lever to safe and continue with the Adams Arms installation.

The first step in installing the Adams Arms system is to remove all of the existing DI parts. Separate the upper from the lower receiver by pushing the two retaining pins here on the left side of the lower receiver. Next, pull the charging handle and bolt carrier group back and out of the upper and set it aside. Remove the bolt from the carrier and set the carrier aside. To do this, you will first pull out the cotter pin found here on the left side of the carrier. Next, shake the firing pin out of the back of the bolt carrier. Sometimes it will stick a bit and you will need to bang it against a hard, flat surface to get it out. Then, rotate the can pin found at the top of the carrier 90 degrees and lift it out of the carrier. Once all of this is done, the bolt will slide freely out of the front of the carrier. Once the bolt is removed use a thin, flat edge surface, like a pocket knife, and remove the gas rings. This can be done by placing the flat edge under the top ring and lifting it out and up as shown here. Do this for each gas ring. Then place the bolt spring on the back of the bolt and reassemble the bolt carrier group as shown here.


Next, remove the hand guards by pushing the delta ring down towards the receiver with one hand. While holding the delta ring down, use your free hand to pull the handguard off. Remove the portion of the handguard held in place by the delta ring, first by pulling it away from the barrel nut, than remove the other end from the handguard cap by pulling down and out. This task will be easier if you have a handguard tool. Once you have removed the handguards, place the upper either on a vice block or secure it in a vice making sure not to damage the outside of the upper receiver. Using the 3/4″ wrench or an armorous tool find the two flat surfaces on the flash hider for the wrench and turn the flash hider counter clockwise to loosen and remove that part along with its washer. After removing the flash hider, remove the upper from the vice.



The last step of removing the DI parts is to remove the front site. This will be accomplished by driving out the taper pins on the bottom of the front site. Some of you may find this more difficult than others. If you have a front site bench block which looks like this, use it as a rest to remove the pins holding the front side in place. If you do not, look at the pins and determine which side of the pin is smaller. In this case the left side of the taper pin is smaller than the right, so we will be driving the pins from the left to the right. This will be the side you will be driving from. Using your 1/8″ hardened pin punch and a hammer drive the front site pins out. This may be difficult because some of the pins go through the barrel. Once the pins are out, remove the front site by pulling and twisting the site towards the front of the barrel. Sometimes this can be difficult and you will need to hit the front site a few times with a rubber or plastic hammer to get the movement started. Use a rubber or plastic hammer so you do not damage the front site. Remove the front site completely and the hand guard cap if your AR has one. Once the front site is removed, screw the flash hider on about half way or until it is hand tightened to protect the thread for the next part of the installation.


The following is a list of all the parts of the Adams Arms Piston Conversion System:

  • Gas block
  • Drive rod with drive rod spring and drive rod bushing
  • Gas plug
  • Modified hand guards
  • Modified hand guard cap
  • One piece bolt carrier
  • Receiver bushing
  • Bolt spring
  • Dowel rod

Now that we have removed the old DI parts, it is time to start installing the Adams Arms system. The first thing we will install will be the receiver bushing. First, you have to clean the hole in the receiver where the gas tube was and where the drive rod will be going. You will need to use a cleaning product like break parts cleaner or mineral spirits that leaves no oily residue behind and dries clean. Next, coat the outside of the receiver bushing with heavy grease preferably Vaseline or something similar. Dip the tip of the dowel rod provided with the system in the grease making sure to put a heavy coating of the grease at the tip of the rod. The grease on the dowel rod will hold the receiver bushing on the tip of the rod to line up for installation. It will look like this. During this step, place the upper on the hard flat surface with the tip of the flash hider resting on the surface and the back of the receiver pointing up towards the ceiling, like so. You will notice there is nothing inside of the receiver at this time. Gently place the bushing into the gas tube hole at the top of the receiver. You need to line up the bushing to make sure it is going in straight. Once you visually align the bushing, push down on the dowel rod. This seats the bushing into the hole straight so you can begin driving it in using a hammer. While you hammer the bushing into the hole, watch that it doesn’t begin to go in at an angle. You will also notice when you do this right that the dowel rod is not resting against the receiver. When you see the top of the bushing just below the edge of the gas tube hole, stop hammering. A properly installed bushing will look like this inside the receiver. Please note, if your bushing goes in without any type of resistance, in other words it just falls into the hole, use red loctite and coat the outside of the bushing to hold it in place. Make sure you don’t get any of the loctite inside the hole of the bushing, place the bushing in the receiver and let it dry for 36 hours. Once the receiver bushing is installed you can remove the flash hider again.


During this next step we will install the gas block. With the flash hider off, slide the gas block with plug installed onto the barrel with this end pointed towards the muzzle. If you were going to use our modified handguard cap, put this on first. The gas block will rest on the shoulder which is here on the barrel. Some of you will come across an AR barrel that will have a harder time installing the gas block than others. If your AR is giving you difficulty, don’t scratch the barrel trying to install a tight gas block. Here is what you can do to install the part without damaging your barrel. Remove the screws from the right side of the gas block and screw them into the left side. Tighten these screws until you see the tip of them start to show inside this channel in between the two legs of the gas block. Once you see the screw tip, stop. Place a smaller Allen key inside the channel like this. With the short end at the front of the gas block pointed away from the barrel, make sure the Allen key is directly between the gas block leg and the screw tip. Tighten the back screw first until it is snug against the Allen key. Do the same with the front screw. This should allow the gas block to go onto the shoulder of the barrel without any resistance. Once it is in the area it needs to be, loosen the screws and remove the Allen key. Then reinstall the screws into the gas block the correct way. You will tighten them down just enough that you can move the gas block with your hand, but it will not move on its own. Any other adjustments that are needed will not damage the barrel.


If you are using our modified plastic M4 style handguards provided in the system, you will have to first visually look down the receiver at the gas block, and align it with the upper to the best of your ability. Later, we will go over how to check and fine tune the alignment. Check the gas block alignment by installing the drive rod in the gas plug without the spring or bushing. If the drive rod moves smoothly in and out of the receiver and can be moved by rocking the end of the upper up and down, then you have the gas block aligned.


Now that you have the gas block aligned, let’s make sure the drive rod spacing is correct. We recommend our system to have between 15 and 25/ 1000″ for proper operation. This is the best way to get that space. Tighten the screws on the gas block just tight enough so that the gas block doesn’t move unless you force it. Put the gas plug and drive rod still without the spring or bushing into the gas block and turn it to the 12:00 position to lock it into place. Then put the bolt carrier into the upper receiver and hold it into the battery. Point the muzzle of the gun toward the ceiling, and allow the drive rod to rest against the carrier key. You should notice a gap between the gas block and the drive rod sleeve. Measure this gap with a feeler gauge, or if you don’t have a feeler gauge use the width of two standard business cards put together. Adjust the gas block if needed to obtain this space. Once you have the approximate gap, recheck the alignment and torque the gas block screws to 90 inch pounds or until they are properly snug. After everything is tightened down and the rails have been installed. Recheck the alignment and spacing as instructed before. Give any loctite use 36 hours to dry and your AR Retrofit System is ready for action!


For more information on the Adams Arms gas piston conversion kit installation visit

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