404 Jeffrey,450-400 nitro, 416 Rigby 318 Wesley, 8mms amused, 375 express.
If you look from other perspective, just research which factories today make this ammunition?
Very few.
Generally, what someone has said recently, it is not guntopia, there in Africa to make a pick.
Available rifles calibers in camp where I was hunting, were: 375 HH, 300 win mag, 300 HH, and 223.
The calibers you mentioned, only recently, maybe since nineties, are just making revival on the west and clients are bringing them.
Apart for commom ammunition in medium caliber (.30 or so), speaking for DG calibers now:
At one low point, in seventies, or eighties - the only commercial rifles and commercial ammunition were 375 HH and 458 win mag, for bolt actions, as big factories stopped producing ammo in tropical calibers, and rimmed cartridges for doubles.
Only recently few factories started producing "classic" cartridges, and thing change slow. Gun makers follow with new rifles chambered for "classics" but they are not cheap, so revival is slow.