Remington Shotgun Cleaner (has a pic of a clay bird on it). It doesn't harm camo finishes or wood. If you don't have camo, and can keep it off the wood, Crappy Tire makes a de-greaser spray. For the gas piston in a semi, I let it soak in Hoppes No.9 over night, then spray it down with the Rem Shotgun Cleaner.
Rem lube is ok, but G96 Gun Treatment is way better in my opinion. Although I use Rem Dry Lube (Teflon) on my recoil spring and recoil spring tube.