Just adding to the above comment that such structural integration almost certainly represented billets of additional dimensions and involving considerable extra final machining effort.  These products heralded a pre WWII era when labor costs were materially lower than post war markets to come.  These integral front sight ramps/bases now seem quite elegant.  Fitment of such barrels extended into the postwar era.  Yet late forties/early fifties, perhaps depending on model and barrel stocks on hand, the soldered on ramp configurations replaced their forged predecessors.  The net practical effect was essentially nil for sportsmen.  Yet it undoubtedly provided a material boon to the Winchester firm’s cost control measures; such combating an ever increasing shadow on profitability.  

My take.