Found This a couple months back has A blue tone. Also perfectly centered underneath Lincoln chest on the rim it has an S inscription.
If I am not mistaken General Motors Had a trial Run for A couple of years with their experimental Roller press. In the end it was never adopted by any of the Mint Facilities. But they did however Strike quite a few coins. Google "1985 mint tries out new roller coining press". At the Bottom of that page it shows some Lincoln cent pattern examples.
A couple of problems with your Lincoln test pattern. 1. The machine was only used in Philadelphia which makes it highly doubtful they would use a Denver mint mark. 2. They only produced regular cents in 1969, possibly as early as 1968............not 1964.
They could have used the old busted dies from 1964 denver to strike a few test coins. Lincolns nose is Broke off and the S inscription is a bit strange. It would be easy to mail an old working hub or dies than the whole machine press. JMHO Nice Coins with no inscriptions.
I do not believe that the dies were the same as the vertical press dies, as they were mounted for rotary action. When postage stamps were converting from verticla presses to rotary presses, the size of the stamp was slightly different in size, and a stamp is relatively flat vs. a coin. Also these early tests were with nonsense coins as to details ( see pgs 50-51 of the book. The 's' may have been added by people trying to convince others that it was a rare 64-D produced in SF as there were none that year from SF.
I thought the S stands for staff. The denver working hubs could have been used to stamp impressions on the special rotary dies. Did you see the colored GM patterns pictures, the pictures from page 49 50 51 are black and white and are hard to see anything from those pictures.
The "S" on the edge could be explained by a dropped letter that fell from the dies and got stuck inside the collar before the next coin (this coin) was struck. edit - in other words it's an ordinary '64-D coin.
The roller press tests were in 1965 -69 (and the press was eventually set up in the new Philadelphia mint that would open in 1969) Supposedly some 1968 and 1969 cents may have actually been struck using to press but no 64's. Most of the pieces struck by the press are test designs or "nonsense" piece. A good article including images of the test pieces can be found at http://books.google.com/books?id=Rz...A#v=onepage&q=1969 roller press trial&f=false
Better pictures can be found here http://boards.collectors-society.com/ubbthreads.php/ubb/showflat/Number/1739975/site_id/1#import
