So here is my longshot. Inside it is bored for better airflow and has an AR spring over top of the stock spring for substantial more power.
With "silencer" barrel extension
The pump foregrip is made from two 2" couplers, balsa, and lexan for the transfer bars. The PVC is cut to form with the lines of the rifle to allow for maximum area to grab onto. Balsa rails ride against the lower side of the rifle. Lexan bars run along the side of the rifle to engage the charging handle. Very similar to Captain Slugs. Portions of lexan are bonded to the side of the rifle. These pieces engages the charging rails from the undersiade and prevent the rails from buckling and also lock the forgrip in place and prevent it from falling away from the rifle. To remove the unit you just pull the chargin pin and rotate the unit away from the rifle.