Lancaster-

This pair of images has very much set me free around the use of modern thin brass cartridges, which for almost all purposes are nearly useless as supplied.

The WR Explora is a legend.
Not many folk understand what goes on inside the WR Explora ammunition.

Look here

Now look here
Stepped paper liner, 'glued' in place with a 'base-wad', likely some sort of rubberized (or not, whatever...) glue back near the primer. The bullet sits on the smaller diameter 'step' of the paper liner!
This image tells a very good story of the construction of the case, also it clearly shows the swaged construction of the lead bullet/constructed stamped brass nose cone pieces, that's what clearly appears to be a four-petaled base, formed as the teat that is captured by the swaged lead. The stamped nose-cone form is obvious.

I hope these two images help inspire the imagination of other bore-rifle and paradox enthusiasts!

--Tinker