First/foremost - Double check that both mag and chamber are EMPTY - It's best that the lever be left DOWN/bolt OPEN.
Remove the vertical screw from the bottom of the front end of the mag tube, and being careful to contain the magazine's end plug there from flying out under spring pressure, gradually work it out towards the muzzle until the plug and the spring can be removed from the tube.
Tip the rifle muzzle down and tap the rifle, so the follower slides out of the front of the mag tube.
Drive out, from left side towards the loading gate side, the mag tube ring/hanger pin that holds the tube in place, then remove the screws and forend cap from the forend wood to allow the tube to be removed, via sliding it out forward.
The forend wood may now be removed - but be careful, since it could easily catch and splinter on the internal hanger that accepted the cap screws.
Also, handle the now unsupported wood gingerly, since if it cracks, you'll be S.O.L., and need a replacement.
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