A blast of water, followed by WD40 (Water Displacement#40) and clean normally. Rust will first gather in the gas tube assembly if anywhere, so extra care here. 60 seconds more than a normal clean and lube for any other other rifle.
Water base is the only thing to remove salt.
Other fluids such as wd40, Hoppes, Eds Red, CLP, ect will not dissolve salts. Try it if you don't believe me. Dump a teaspoon of salt into one of these fluids, shake well then strain it through a coffee filter. Put the salt back in the salt shaker when done.