Originally Posted by George Burdell
Anyone know how to change the hop up rubber? I don't like the stock one.
Dial the hop up back to original position first.
Remove the flash hider (the thread is counter-clockwise, so turn it clockwise to loosen it, and some models have a small hex screw at the bottom of flash hider), front sight (punch out two pins), hand guard, gas tube and get to the delta ring. Unscrew it (clockwise thread, so turn it counter-clockwise) until you get the entire front barrel assembly out. The inner tube should fall right out. Get ready to catch it, don't just let it fall right to the floor.
The hop up rubber is sandwiched by 2 metal pieces and secured with a metal ring/tube thingy. Pull that metal ring/tube (towards the front) and the 2 metal hop up piece will just come apart.
You can access the hop up rubber now. The notch on the inner tube matches to the nib of the hop up rubber.
Assembly is reverse of the procedure. You may notice there are two small grooves on the inner tube, one near the hop up and one near the front of the inner tube. I am not exactly sure what they are for but I put two small o-rings on there which help to stable the inner tube. Or two revolutions of scotch tape will do the same job. You will feel slight tightness when you reinsert the inner tube if you did this mod. I did this cause when I changed to 363mm inner tube, I noticed slight play hence I did the mod.
Hope this helps.