Not true. Bear with me. A barrel nut will/should fit over the muzzle device - post pics of your muzzle device for confirmation. Now, take your gas tube out of your gas block (whatever it is), cut the gas block off, and take off your barrel nut. Should slide right off and over most muzzle devices. Put on your freefloat rail/tube barrel nut, tighten it down. Mount up a 2-piece gas block. YHM makes a couple. One has a flip-up front sight on it, and the other is the YHM Specter. Wouldn't call the Specter a true "lo-pro" gasblock, but it'll clear any tube that has a 1 5/8" inner diameter. Insert your gas tube and pin it, mount up your freefloat rail. Done.