This one should probably be posted in the wildcat section , but here we are so here goes nothing...

I have an RWS .404 Jefferey case necked down to .30 cal. Case length overall is 2.623" . length to shoulder is 2.450" , width at shoulder is .533". It has a very sharp shoulder angle.
The case came from a Ruger No1 custom rifle estate sale - I managed to "acquire" a single specimen. But my query is - what is this calibre called ? Any suggestions?
I have a scan of the case but need to revisit how to post it here - will attempt to do so tomorrow.

Hopefully this will have an image included.....

This is the fired case. Note the very sharp shoulder angle ( assuming it isnt too small to see anything anyway ). I am sure this has a set name , can some one tell me please ?