I routinely remove a lot more than 4-6 ounces... a myrtle stock I got real aggressive on is right at 25 ounces with pad and LA 700 mag box.
I drill a 1 1/4" diameter hole until I get to nervous to continue, then step to a 1" bit and drill until I am too nervous to continue, then go to a 3/4".
A caliper to measure the wall thickness is pretty easy to make and use to keep the cutter away from the side of the stock...
A series of these stepped holes gets a lot of weight out. I usually use three overlapping.
I take a lot of weight out of the fore end and fill it with fluffed epoxy (microballoons) and cut off sections of fishing rods. Lots of air and stiffness together.
As for laminate stocks... It is easy to get a lot of weight out of them because they are so much denser than real wood...
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