Re: walter ppk info???
The marking is poorly stamped, but it is a crown/N, the standard commerical Nitro (smokeless powder proof of the period. The serial number dates to 1935.
The grips appear to be American, probably Franzite.
FWIW, that stamp is not actually on the barrel, but on the part of the receiver into which the barrel is inserted. There should be a similar mark on the barrel itself right at the muzzle end.
The RZM, Reichszeugmeisterei, which translates roughly as National Quartermaster, was the supply service for the Nazi part and its various organizations. It sold all kinds of clothing and equipment to the party faithful, with profits going to the party (or to high ranking officials). It was a big organization, large enough to have companies, like Walther, make specially marked goods for it. The national headquarters was in Munich but there were regional stores around Germany.