Entry Level Cherrypicking - Re-punched Mint Marks & Over Mint Marks

Understanding re-punched mintmarks and how it happened.

The 1950's were a strong decade of dominance for
the re-punched mintmark.  They can be found
pretty regularly and most circulated examples sell
in the $1.00-2.00 range.

Going back into the 1800's when the established mints were experimenting with adding mintmarks to the coins, the tiny letters were hand punched into the working dies.  How it worked was the mint employee took a thin steel punch with the letter on the tip, he/she then sets it on a designated area on the die face and then taps the punch with a small hammer to leave behind the impression of the mark.  In some instances, the marks had to be reset and re-punched into the working die for several reasons.  One is the mint employee inadvertently punches the incorrect mintmark on the coins, therefore causing a secondary punch to correct the mistake.  Second, if a mint employee punches a mintmark weakly or out of place, he/she would have to re-punch the mark.  In turn making a permanent impression of the repunch on a planchet when it's struck through the minting process.  There are cases where the mintmark would be punched up to 5-6 times in one go, making for a very dramatic minting variety.  

Over mint marks were created much the same way.  In this case, a D (Denver) mintmark can be punched over an S (San Francisco) mintmark and vice versa.  These mintmark varieties are not nearly as common as the same mint re-punch and are generally more tougher to find in circulation.  For example, the 1944 D/S Lincoln Cent and the 1954 S/D Jefferson Nickel are some of the well known and most sought after over mint marks in existence.  And therefore these possess a much more robust secondary market.

Here's a great example of an earlier 1930's
RPM.  As you can see, there is a well
defined separation in the serifs of the "S".

Where's a good place to find them?

Typically I'll tell any novice cherrypicker to start with your pocket change, specifically anything before 1982 and focus on the Lincoln cent series.  There is a large population of RPM's in the 60's and 70's Lincoln Memorial cents than any other denomination for that time period.  A good condition RPM in any date in this range is an outstanding find, as these are an easy sell in the $.50-1.00 price range.  It may not seem like a whole lot, but where else can you get 50x-100x your face value?  I've personally had the pleasure of finding several dozen examples out of a $25.00 bank box of cents.  

Once you've recognized and experimented with the 60's-70's coinage, the wheat cent series of the 40's and 50's are another great jumping up point.  These are the magical years for RPM's.  And finally, once you've established a great wealth of knowledge of the subject, try your hand at cherrypicking in dealer stock boxes. Where you can dive into the more pricier series like the seated liberty's and Buffalo nickels.  Every RPM and OMM is worth many times over face, so why not exhaust all of your resources?

For as long as I've been in numismatics, i'm still very fond of this date range and to this day I still search for RPM's and OMM's.  Searching 10,000 wheaties in a month for 12 months, generated over $5k in profit for the 2012 year.  Again while not a huge profit per piece initially, a total collection is worth near a king's ransom.  So why not give it a try?

Good luck hunting!