Rimfire ammo is filthy, and it will bake into a hard carbon crust which is difficult to get off if you shoot dry, or if you use a traditional lube then it'll just bake on even harder. A synthetic lube like BreakFree CLP doesn't cook off. I keep the action wet. You wouldn't believe how easy is it to clean up afterwards - a simple wipe with a cloth. Before I used to have to soak in solvents, then use a toothbrush to get at the baked layers. Now, instantly wiped clean. Amazing stuff.