I am on vacation in Russia and was given several spent .38 bullet shell casings as a souvenir. They were fired recently and presumably still have residue on them.
I'll be flying domestic within Russia and the United States, and international from Moscow to San Francisco with a layover in Frankfurt. I would like to bring the shell casings home with me, but only if they are unlikely to cause any problems.
My plan is to put them in a ziplock bag, all alone in an outside pocket of my checked suitcase.
Is this likely to cause any problems either within Russia or the US or on the international flights? If so, is there anything I can do do mitigate the issues?