You can find bull barrels of several types here:
Cheaper Than Dirt

I've been eyeing a compensated fiber wound ultralight bull for some time now . A .22 doesn't really benefit from the weight of a solid bull since the recoil is low , but the additional stiffness and compensator should improve my groups . They also have a good selection of stocks and trick parts for them . Occasionally they even carry a kit that turns it into a copy of the MG-42 machine gun , squirrel hunting with that rig would really turn my crank . Can you imagine the looks you'd get toting that nasty looking rig into the woods ? LOL