The following Thread is to discuss the Installation of the AR-15 Crush Washer as well of proper removal information. For the purpose of simplifying the information we will be using the standard A-2 Flash Hider as an example and you can compare it to your future equipment installations using the Crush Washer.
First of all, a good solid vise or holding device must be used. In addition you must assure that the barrel can not turn in the holding fixture while installing the Crush Washer. I use a 4" Heavy Duty Vise with nylon jaws and angle the barrel in the protective jaws so that part of the Front Sight Assembly is also clamped in the vise so the barrel will not rotate and damage the finish when installing the Crush Washer. This same method will be used when addressing the proper techniques of removing a Crush Washer that has been used more than one time causing the need to cut it off as below.
The Crush Washer is different in configuration on both sides. One side has a recessed side and a dome side. I refer to the recessed side in the schools as the side that if you can imagine, looks like a cereal bowl. I have them lay the Crush Washer down on a flat surface with the recessed (Bowl Side) facing up. When installing the Crush Washer this side goes to the Front when on the barrel and the dome side goes against the barrel.
Then the Flash Hider in this example is screwed on the barrel by hand "Only" until it makes contact with the Crush Washer. *Note! If the Flash Hider needs turned 3/4 or more of a turn to be in the correct position, or less than 1/4 turn try another Crush Washer. Knowing that in this case, the A-2 Flash Hider has 5 ports on it and when properly installed the center port should be in alignment with the Front Sight Post. The need to turn the Flash Hider 3/4 or more to be in position will be difficult if not almost impossible and certainly add more stress than necessary to the barrel. Likewise if the Flash Hider would only need tightened less than a 1/4 turn using the wrench it could easily come loose. DO NOT USE A WRENCH to check this! So after checking the above locations when hand tightened just to the point of contact! If the hand tightening check shows that the Flash Hider has less than 3/4 turn to go or slightly more than 1/4 turn to be in the correct position you are good to go and *Begin Using the Wrench. *If when hand checking you have 3/4 turn or more to turn or Less than 1/4 turn try another Crush Washer! Generally there is a few thousandths difference in thickness between Crush Washers and you can find one that conforms to the less than 3/4 to 1/4 turn. In certain rare occasions you can not solve the alignment problem you can also change Flash Hiders in this case since threads start at different points when produced. USING THE WRENCH: The standard A-2 Flash Hider requires the use of a 3/4 Wrench. The word CRUSH WASHER is just what it implies!
After getting a proper hand tightened location of less than 3/4 to 1/4 or more you can now begin using the wrench. When tightening the Crush Washer you DO NOT! just crush it all the way around until it goes to the correct position. This will not normally work anyway if you have a long way to go! So you apply pressure to the wrench tightening the Flash Hider against the Crush Washer a little bit at a time crushing the Crush Washer and then backing it off "slightly"! "Do Not Back It all the way off of the Crush Washer releasing the pressure! For example you tighten it about a 1/4 of a turn at a time then back off about an 1/8th. releasing the pressure *just slightly* than start tightening it another additional 1/4 for example. Repeat this procedure until the Flash Hider is in position.
CRUSH WASHER REMOVAL:
When removing a Crush Washer they should *NEVER BE USED AGAIN! Should you use it again it will crush to the point where it crushes between the front face of the Barrel and behind the threads on the barrel where the thread free portion of the barrel is located. You will not be able to remove it should you ever want to take it off in the future.
Should this situation occur here is the method that I use to remove them. I use a Portable Battery Dremel Tool with the Dremel 1 1/2" Metal Cutting Discs. They come in the Dremel EZ Lock Cutting Kit. Product Code
REEZ688-01. You will need to use a Vise or some other sort of rigid stabilizing device due to the fact you as well as the Barrel must be absolutely stable during the cutting and removal process. As mentioned, at the beginning of this Thread I position the Barrel in the Vise as stated above. Clamp a small pair of Vise Grip Pliers on one side of the Crush Washer. Pull the Crush Washer out toward the rear of the threads and angle the Crush Washer at about a 30 degree angle with the Barrel. This helps to prevent damage to the barrel or the threads. Clamp onto the Crush Washer and hold it tightly using the Vise Grips. You must keep control and hold the Vise Grips securely. Then turning the Dremel on to around 6000 RPMs I begin contacting the Crush Washer at around a 45 degree angle. Use extreme caution and cut down as close to the inside edge of the Crush Washer as possible, using caution not to contact the barrel or the threads on the Barrel!
You do not cut all the way through the Crush Washer because if you do you will no doubt hit the barrel or the threads. Cut close and STOP! Then rotate the Crush Washer on the barrel and reattach the Vise Grips 180 degrees on the opposite side of your initial cut and repeat the same procedure on the second side. Once you have got both side cuts to that point you can break the Crush Washer in half and remove it. Moral of the Story! DO NOT REUSE CRUSH WASHERS!