The replacement mag well Bob refers to is the Accurizer. It is standard bottom 'metal' with with a steel pillar set into the action screw hole (front of trigger guard) preventing the plastic being crushed and cracked when torque is applied. It's a bit dear but nowhere near as expensive as the Styria bottom metal and it doesn't weigh 3lbs!
https://www.seidler-waffen.at/buechsenmacherei/steyr-accurizer.html