Hi David,
The plastic Swiss magazines started with the M1929 Swiss Lugers made in Bern CH. The plastic came in red, then brown, and finally black. Red is the most desireable of the three...
If you read a recent posting in the Swiss Luger section, you will learn a bit more about the scriptic "P" on the metal spine of this Swiss luger and the little swiss crosses stamped, sometimes, in the plastic "buttons" of the magazine bottom.
Regards,
Pete... <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />