Here's some info on wear rate from another forum I check out. It's the Tom Dankowski (Nasa-Tom for all you MDer's) forum.
http://www.dankowskidetectors.com/discu ... #msg-10190"I'm quite short on time at the moment...........but...........a short answer for silver,,,,,,,,,,,,,as...... I believe this is would most want to know.
A Barber dime & quarter will go from MS-65 to G-4 in approx 3-1/2 years of 'regular' circulation. (Barber half dollars took about 4-1/2 years). The determining factor of the 'grade' of Barber coins is the letters "L I B E R T Y" in the headband. THEY WORE QUICKLY!!!! Most folks do not realize how 'soft' silver is.
A Mercury dime would wear from new condition (MS-65) to Fine (F-12) condition in approx 13 months. Then another 5 years of regular circulation......and the coin would be in Good (G-4) condition. This is to say that; just over 6 years of circulation...... a silver Mercury dime would be in G-4 condition.
This 'model' above is a good representation for how other silver coins would wear.
I had one of the neatest occurences many years ago. I found a very tight/focal coin spill that.........4 of the coins were Barber Quarters. Dates were 1895, 1902, 1909 & 1916. The 1916 was VF-30, the 1909 was G-6, the 1902 was G-4..........and the 1895 was barely a G-4.......a very flat quarter. It appeared the 1909 'survived' a bit longer than 'norm' model. Maybe in a piggy bank for a handful of months. BUT, still...... all fit within the normal wear model.
Two years later, I found a nearly uncirculated 1919 Mercury dime stuck to a G-6 (almost VG-8) 1916 Mercury dime. Definately from the same pocket.
Many more 'coin spills' to validate the above data. Also Q. David Bowers has written several books on silver U.S. coins.......and he covers 'how quickly' these coins will wear. He does a superb job on the Barber series coins. If you need more info on his publications.....just holler.
A redesign of a coin does not appear to have much of a effect, IRT the removal of the older design. Indian Head pennies were still in circulation in the early 1950's (although a bit sparce)..........Shield nickels were still in circulation in the 1920's...............'V' nickels were still in circulation throughout the entire Buffalo nickel era. Seated Liberty dimes/quarters/half-dollars were in full circulation throughout the entire Barber coinage era......and all the way through the 1930's. Wheat pennies were still in circulation in the early 1980's. This specific situation about the wheat penny is a bit unique in two respects: 1) there were MANY more coin collectors in the 1980's (vs earlier years), and 2) pennies are the easiest to collect."