Super easy Studio Series Bonecrusher mod- cut out the plastic between his smaller claws, so they can move separately.
You can do the same with the larger claws, but this might cause one of them to fall off easily. I did it on one side, and the claw fell off, so I had to use a small screw to hold each pair of claws (1 large, 1 small) on. The other side, though, held on, so I used a drop of super glue on the end of the pin to reinforce it. So this one may just be the luck of the draw- if the large claw on the end of the pin is tight, you may be OK, but if it's loose, it will likely fall off, and you'll have to use screws or a new pin or some other solution. YMMV.
A bonus to cutting apart the large claws: they fold away more tightly in alt mode.
Robot mode pics shortly.