Interesting

[Alan de Enfield]

So Bruce the Mk8 Z'eds were exclusively for the mg's to give a good beaten zone at extreme range so they went up 6 grains are the 8'd loaded any hotter than say the MkVII ball ammo.
I have read what you speak of in relation to the wound characteristics of the MkVII ball round it definitely had an impact whether by design or fluke how its dynamics worked when deforming and tumbling inside.

MK8s were 'primarily' used for MGs but their use was also 'allowed' in rifles 'Stens' etc whilst doing night patrols (due to the reduced flash of the NC)