That was just a piece of 303 bar to hold the button in place for the photo, I haven't decided if I'm going to use the original hole and pin arrangement, or use two brass screws and the shaping is a long way from finished.
Two ways to do the forearm. One is float everything generously and make bands of electical tape to keep the forearm off the barrel the amount that you relieved it and then bed the magazine tube to the forearm and the forearm to the receiver with RTV silicone. After that has cured, bed the barrel to the barrel channel with silicone. The magazine tube holds the firearm in position, the front magazine screw (into to the dovetail at the muzzle) holds both, and the forearm/magazine tube have a little cushion back at the receiver to stretch/contract without putting excessive pressure on the barrel as it heats. The silicone dampens harmonic vibrations and keeps them consistent as things move.
The other way (if your rifle has two bands and no dovetail or forearm cap) is to create an anchor for the forearm by filing a notch in the bottom of the barrel and bedding a piece of hardened drill rod into the forearm with epoxy to lock the two together. Then the mag tube is bedded with silicone and the forearm to the receiver with silicone and the barrel allowed to float in the channel. The forearm band holds everything together and should be relieved to just barely put any pressure on tje bareel when installed. The notch in the barrel for the band screw should be relieved so the screw doesn't touch.