I've got a jar full of no-date buffalo nickels, but all have MM's.. I know this is not recommended, but what kind of acid or acid based liquid would bring out the date? The dates are just barely not readable... Yes, I know, don't.
I know that the chemical that does the work is an acid, but I'm not sure if you could get the results with any type of acid. Might be worth a try if you've got some sulfuric or other acid handy.
there was a jewelry makers at a show in NY years ago that was buying no-date buffs. to make head bands and belts. I went home and boxed mine up and sold them. DE