I recently acquired this round, and as you know, am no specialist in this calibre.
It appears to be an early dummy. Unfortunately the headstamp is very finely stamped on a dark background and I was not able to get a decent picture, but it is “18 DM 98 0” with the “DM” in the twelve o’clock position.
The “bullet” is made from sheet and closed with a four petal crimp and the primer pocket filled with a lead/solder material. The whole round has a bronzed appearance but that may be aging. It is in mint condition with no primer strike. Total weight is 281.0 grains.
All and any information appreciated.