[lugerholsterrepair]

Gerben, I guess the rough leather inside works as an abbrasive pad.

I am sure it does! I take apart many holsters during my restorations and you would be surprised at the sand and dirt I find under parts and in crevasses. The sueded underside of Luger holsters undoubtably collect small particles of dirt and sand, entrapped in their strands. This would act as an effective abrasive in most cases. Where the blued metal comes into contact with this material, I would expect it to wear.
Ten times though! That is quicker than I would have guessed.
Jerry Burney