Sinclair Int. catalog 2011-b question

[raddiver]

Odd place for this i know, but while i was looking at the front cover of this catalog, the cartridge shown has captured my attention.
Can anyone tell me what it is?

I think i want to reload it.

edit:
i thought it was a creedmoor or grendel but looking at others online, it doesnt look the same.

 

[cfullgraf]

My guess would be one of the wide body short magnums.

 

[raddiver]

.223 wssm maybe?