after a heavy shooting session or at the end of the season i clean mine with brake clean, make sure to re-oil, cause brake clean removes all lubrication and then coat the external threads with permatex anti-seize and tighten 'em down. when your elbow joint pops thats tight enough.
for you folks that have aluminum heads on your vehicle engines, the anti-sieze works great for spark plugs also. when you screw a steel plug into an aluminum head chemical reactions take place and can make for a difficult removal.
learned that trick from pops yoshimura.