The Barnes bullet would be the 55 grn. Triple Shock. Solid copper, should hold together.

Nosler makes a 60 grn partition.

There is also a trophy bonded bear claw, I think it is 55 grains.

You may be able to get a 55 grain bullet up to 3800 fps with the new H4007 powder. If your goal is to not blow up a fox, you probably should try to load it down.