Some clarification. Belted rounds IMO are for mag fed guns and rimmed cases are for doubles. I think that clears much of this up.

My point is a properly sized and shaped belted or rimmed round has more clearance and taper than a modern headspace on the shoulder round. This extra clearance and taper allow the round to be forced into and fired in a chamber which may have a spec of something in it.

Rounds which headspace on the shoulder must have minimal clearance at the shoulder of the chamber so they are pushed back against the breech face or bolt face. This fit makes them inherently more picky about this dimension. If a spec of crud is on the shoulder area of the chamber it will be very difficult, or impossible to force the bolt closed. A 0 taper case adds to this by forcing anything on the side of the chamber on to this shoullder surface as it is fed.

So, bolt and doubles have their place. Besides, whether hunting browns in AK or cape buffalo in Africa, I don't want to be stomped or eaten because a spec of poo was in my chamber. I want to force and fire.