Parker Reproduction shotguns made by Winchester are usually marker with a
serial number that begins with the gauge of the gun, which is followed by a dash
and then five digits. For example, a 12 gauge serial number might look like
12 - 00123. But, there are some guns seen where the gauge is
replaces with a P; for example P - 00123. In this case the P
stands for prototype.
The first P numbered gun was P - 0026. It is not know how many
prototypes were built. Prototype guns were not "given away" as gifts
etc. If you wanted one, you ordered it just like anyone else, and you paid for
it at retail prices.