Laquer thinner(also found in the form of nail polish remover) may also work.
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If the Q-Tip won't loosen it up enough to get it out of the lettering completely and you need something to scrub it out, don't be tempted to use an ordinary toothbrush w/ acetone or laquer thinner.
Those solvents will dissolve and melt the plastics in most tooth brushes and bristles into a gooey mess onto the metal necessitating further cleanup.
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Either a common artists brush with a natural wood (unpainted) handle or a military M16 cleaning brush (commonly called and looking like a 'toothbrush') will work w/o dissolving before your very eyes. Clip the artists brush bristles short for a better scrubbing action if needed.
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Make sure the grips are removed as tbury says or you'll damage the finish on them if the solvent splatters there.
Also tape up or cover up any front site plastic inlay and white outline on the rear site blade. They're vulnerable to damage too.