I can vouch for the acetone. It isn't very expensive and is readily available for painters in the hardware department of chain stores.
Water will be absorbed by the acetone, and it will evaporate from the pistol very quickly without hurting the surface finish. I buy it by the gallon for use on my coin collection. And it works well to degrease metal before cold bluing.
There are several cautions however. One, the fumes are not good for you, so use ventilation. Two, it is flammable (inflammable) so be careful with sparks and flames. And three, it will melt some plastics, so be careful of grips, sight inserts and anything on the workbench that might get splashed. Use safety glasses.
And I never return the used fluid to the original container, but store it in a second container where it will be used several more times before being used to remove bumper stickers. The last gallon I bought from Walmart was about $15.