Seems like I recall PO Ackley writing of these in his books. I think some folks wild catted some cartridges by forming belts on standard cases - might have been part of the early 1960's "belted Magnum craze". It might have been a cheap way to make 240 Weatherby cases too - I think that case has a 30-06 head size but a belted case.
More recently folks were turning off the belts of some brass.
We shooters sure like to mess with stuff don't we?