I used a sneaky trick to protect my fingers- - - -a small piece of aluminum plate with holes in it threaded for the plugs, held with a pair of vise grips during the cleaning operation. A quick blast of compressed air completed the cleaning procedure. We carried a few sets of plugs in the tool box that way, already gapped and ready to install. The plate also kept the bead blast media out of the threads.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!