.380 Revolver hstp

G’day. I got a round of .380 Revolver hstp’d “R^L 42/.380/II Z” (12/6,^=broad arrow). I assume that it is 1942 manufacture from Royal Laboratory. Would it be fair to assume “II Z” refers to Mk 2 cartridge, glazed nitro-cellulose powder?

It certainly does.

The Mark IIz was the service issue round for Webleys, Enfields, S & Ws etc. from 1937 until the end of its life in the late 1960s.