Correct Enfield pattern rifling available today...

[Alan de Enfield]

AdE
Was the Mkv1 not a FMJ with an open base. I know the Indian DUM DUM had exposed lead tips but did it have an open base. I dont have any in my collection to examine.
The open base is the key here. I do have some Mkv1 i acquired in England made by an unknown person ( not factory ) to me. They were bought for a particular purpose.

I don't have any MkVI information, but for interest, the 'original' MkVII was actually a 160gr bullet,

I cannot find where I got this info from - so apologies to the author for not acknowledging them.

The original .303" MkVII bt weighed 160 gr and was approved in Mar 1910 and had no cannelure. Production lots of this ammo failed accuracy proof and the bt was redesigned.
The new bt retained the exterior dimensions of the above but the aluminum core tip was shortened and the lead lengthened. The new bt weighed 174 gr and was approved LOC 15629 Oct 1910.
".303Inch" Labett and Meade