Front half-blackened case

After the article in the IAA journal Issue 498 July/ Aug. 2014 pg 38, hit the post office a gentleman sent me these photos asking = what do I have here?

The bullet is GMCS-jacketed and although it looks blueish in this photo he assures me it is black and is the same sort of blackening (he would know this), but not applied by dipping, as those shown in the Journal.

So ladies & gents, help us both please. Any input would / could be important.