M4A1 FSP RIS II
Ensure the firearm is unloaded and pointed in a safe direction. Remove the upper receiver from the lower. If there is a flash suppressor and front sight, these need to be removed next. Remove the old handguards. Using the barrel nut wrench remove the existing barrel nut. Place the barrel nut collar over the threaded portion that the barrel nut was removed from. Install the new barrel nut, after making sure the gas tube hole is correctly aligned, tighten the barrel nut down and install the new handguard using the included Allen head cap screws.