It means that the person doing the stamping couldn't be bothered to change the stamp to the correct day.

(not kidding)

Or,could be 10 in Roman numerals...but proly not!

I had a feeling this was it... thanks for the reply

I had a old slinger shell that had a capital P stamped inside..

decent size stamp..@ 2" high and 1" wide..

I remember somebody telling that it ment that the shell was considered a good shell (round and the wood grain was desireable to use in a premium kit.

Not sure what the X means..

I could be mistaken, but I thought a P stamp meant the shell had some kind of wrap on it? Sparkle or Pearl. As opposed to being a natural finish.

Never seen any with an X on the date though, sorry =/

From http://www.vintagedrumguide.com/painting_shell_interiors.html

No idea what the x was, but I do know that the large P stamp stands for Pearl. As in Pearl wrap, an indicator to the next step in the assembly line. The M stamp stands for Maple, or Maple finish. The shells that were better suited to being wrapped because of slight exterior blemishes received a P stamp and the shells that were perfect and suitable for clear lacquer or a stain finish received the M stamp.

you are correct..