Is it legal to put a shoulder stock on an original Mauser C96?

At one time, it wasn't legal (without a stamp), but I thought I read an article in one of the guns mags (a few years ago) that said the C96 could now be stocked, legally, without a stamp.

Is that true?

The stock I'm talking about is the combination wood-holster/stock that was made for the C96.

Any help is appreciated.